John Adams (October 30, 1735 – July 4, 1826) was an American politician and political philosopher and the second President of the United States (1797 – 1801), after being the first Vice President of the United States (1789 – 1797) for two terms. He was one of the most influential Founding Fathers of the United States.

Adams came to prominence in the early stages of the American Revolution. As a delegate from Massachusetts to the Continental Congress, he played a leading role in persuading Congress to declare independence, and assisted Thomas Jefferson in drafting the United States Declaration of Independence in 1776. As a representative of Congress in Europe, he was a major negotiator of the eventual peace treaty with Great Britain, and chiefly responsible for obtaining important loans from Amsterdam bankers. Adams' revolutionary credentials secured him two terms as George Washington's vice president and his own election as the second president of the United States. During his one term as president, he was frustrated by battles inside his own Federalist Party (by a faction led by Alexander Hamilton) and the newly emergent bi-partisan disagreements with Jeffersonian Republicans. During his term, he also signed the controversial Alien and Sedition Acts. The major accomplishment of his presidency was his peaceful resolution of the Quasi-War crisis with France in 1798. After Adams was defeated for reelection by Thomas Jefferson (at the time, Adams' vice-president), he retired to Massachusetts. He and his wife, Abigail Adams, founded an accomplished family line of politicians, diplomats, and historians now referred to as the Adams political family. Adams was the father of John Quincy Adams, the sixth President of the United States. His achievements have received greater recognition in modern times, though his contributions were not initially as celebrated as those of other Founders.

John Adams, Jr., the eldest of three sons, was born on October 30, 1735 (October 19, 1735 Old Style, Julian calendar), in what is now Quincy, Massachusetts (then called the "north precinct" of Braintree, Massachusetts), to John Adams, Sr., and Susanna Boylston Adams. The location of Adams's birth is now part of Adams National Historical Park. His father, also named John (1691 – 1761), was a fifth-generation descendant of Henry Adams, who emigrated from Braintree, England, to Massachusetts Bay Colony in about 1638. He is descended from a Welsh male line called Ap Adam. His father was a farmer, a Congregationalist (that is, Puritan) deacon, a lieutenant in the militia and a selectman, or town councilman, who supervised schools and roads. His mother, Susanna Boylston Adams, was a descendant of the Boylstons of Brookline. Adams was born to a modest family, but he felt acutely the responsibility of living up to his family heritage: the founding generation of Puritans, who came to the American wilderness in the 1630s and established colonial presence in America. The Puritans of the great migration “believed they lived in the Bible. England under the Stuarts was Egypt; they were Israel fleeing ...to establish a refuge for godliness, a city upon a hill.” By the time of John Adams's birth in 1735, Puritan tenets such as predestination were no longer as widely accepted, and many of their stricter practices had mellowed with time, but John Adams “considered them bearers of freedom, a cause that still had a holy urgency.” It was a value system he believed in, and a heroic model he wished to live up to.

Young Adams went to Harvard College at age sixteen in 1751. His father expected him to become a minister, but Adams had doubts. After graduating in 1755, he taught school for a few years in Worcester, allowing himself time to think about his career choice. After much reflection, he decided to become a lawyer and studied law in the office of James Putnam, a prominent lawyer in Worcester. In 1758, Adams was admitted to the bar. From an early age, he developed the habit of writing descriptions of events and impressions of men which are scattered through his diary. He put the skill to good use as a lawyer, often recording cases he observed so that he could study and reflect upon them. His report of the 1761 argument of James Otis in the superior court of Massachusetts as to the legality of Writs of Assistance is a good example. Otis’s argument inspired Adams with zeal for the cause of the American colonies.

On October 25, 1764, five days before his 29th birthday, Adams married Abigail Smith (1744 – 1818), his third cousin and the daughter of a Congregational minister, Rev. William Smith, at Weymouth, Massachusetts. Their children were Abigail (1765 – 1813), future president John Quincy (1767 – 1848), Susanna (1768 – 1770); Charles (1770 – 1800), Thomas Boylston (1772 – 1832), and the stillborn Elizabeth (1777).

Adams was not a popular leader like his second cousin, Samuel Adams. Instead, his influence emerged through his work as a constitutional lawyer and his intense analysis of historical examples, together with his thorough knowledge of the law and his dedication to the principles of republicanism. Adams often found his inborn contentiousness to be a constraint in his political career.

Adams first rose to prominence as an opponent of the Stamp Act of 1765, which was imposed by the British Parliament without consulting the American legislatures. Americans protested vehemently that it violated their traditional rights as Englishmen. Popular resistance, he later observed, was sparked by an oft-reprinted sermon of the Boston minister, Jonathan Mayhew, interpreting Romans 13 to elucidate the principle of just insurrection. In 1765, Adams drafted the instructions which were sent by the inhabitants of Braintree to its representatives in the Massachusetts legislature, and which served as a model for other towns to draw up instructions to their representatives. In August 1765, he anonymously contributed four notable articles to the Boston Gazette (republished in The London Chronicle in 1768 as True Sentiments of America, also known as A Dissertation on the Canon and Feudal Law). In the letter he suggested that there was a connection between the Protestant ideas that Adams's Puritan ancestors brought to New England and the ideas behind their resistance to the Stamp Act. In the former he explained that the opposition of the colonies to the Stamp Act was because the Stamp Act deprived the American colonists of two basic rights guaranteed to all Englishmen, and which all free men deserved: rights to be taxed only by consent and to be tried only by a jury of one's peers. The "Braintree Instructions" were a succinct and forthright defense of colonial rights and liberties, while the Dissertation was an essay in political education. In December 1765, he delivered a speech before the governor and council in which he pronounced the Stamp Act invalid on the ground that Massachusetts, being without representation in Parliament, had not assented to it.

In 1770, a street confrontation resulted in British soldiers killing five civilians in what became known as the Boston Massacre. The soldiers involved, who were arrested on criminal charges, had trouble finding legal counsel. Finally, they asked Adams to defend them. Although he feared it would hurt his reputation, he agreed. Six of the soldiers were acquitted. Two who had fired directly into the crowd were charged with murder but were convicted only of manslaughter. As for Adams's payment, Chinard alleges that one of the soldiers, Captain Thomas Preston, gave Adams a symbolic "single guinea" as a retaining fee, the only fee he received in the case. However, David McCullough states in his biography of Adams that he received nothing more than a retainer of eighteen guineas. Adams's own diary confirms that Preston paid an initial ten guineas and a subsequent payment of eight was "all the pecuniary Reward I ever had for fourteen or fifteen days labour, in the most exhausting and fatiguing Causes I ever tried."

Despite his previous misgivings, Adams was elected to the Massachusetts General Court (the colonial legislature) in June 1770, while still in preparation for the trial.

In 1772, Massachusetts Governor Thomas Hutchinson announced that he and his judges would no longer need their salaries paid by the Massachusetts legislature, because the Crown would henceforth assume payment drawn from customs revenues. Boston radicals protested and asked Adams to explain their objections. In "Two Replies of the Massachusetts House of Representatives to Governor Hutchinson" Adams argued that the colonists had never been under the sovereignty of Parliament. Their original charter was with the person of the king and their allegiance was only to him. If a workable line could not be drawn between parliamentary sovereignty and the total independence of the colonies, he continued, the colonies would have no other choice but to choose independence. In Novanglus; or, A History of the Dispute with America, From Its Origin, in 1754, to the Present Time Adams attacked some essays by Daniel Leonard that defended Hutchinson's arguments for the absolute authority of Parliament over the colonies. In Novanglus Adams gave a point-by-point refutation of Leonard's essays, and then provided one of the most extensive and learned arguments made by the colonists against British imperial policy. It was a systematic attempt by Adams to describe the origins, nature, and jurisdiction of the unwritten British constitution. Adams used his wide knowledge of English and colonial legal history to argue that the provincial legislatures were fully sovereign over their own internal affairs, and that the colonies were connected to Great Britain only through the King.

Massachusetts sent Adams to the first and second Continental Congresses in 1774 and from 1775 to 1777. In June 1775, with a view of promoting union among the colonies, he nominated George Washington of Virginia as commander-in-chief of the army then assembled around Boston. His influence in Congress was great, and almost from the beginning, he sought permanent separation from Britain. On May 15, 1776, the Continental Congress, in response to escalating hostilities which had started thirteen months earlier at the battles of Lexington and Concord, urged that the colonies begin constructing their own constitutions, a precursor to becoming independent states. The resolution to draft independent constitutions was, as Adams put it, "independence itself."

Over the next decade, Americans from every state gathered and deliberated on new governing documents. As radical as it was to write constitutions (prior convention suggested that a society's form of government needn't be codified, nor should its organic law be written down in a single document), what was equally radical was the nature of American political thought as the summer of 1776 dawned. Several representatives turned to Adams for advice about framing new governments. Adams got tired of repeating the same thing, and published the pamphlet Thoughts on Government (1776), which was subsequently influential in the writing of many state constitutions. Many historians argue that Thoughts on Government should be read as an articulation of the classical republican theory of mixed government. Adams contended that social classes exist in every political society, and that a good government must accept that reality. For centuries, dating back to Aristotle, a mixed regime balancing monarchy, aristocracy, and democracy, or the monarch, nobles, and people was required to preserve order and liberty.

Using the tools of Republicanism in the United States, the patriots believed it was corrupt and nefarious aristocrats, in the British Parliament and stationed in America, who were guilty of the British assault on American liberty. Unlike others, Adams thought that the definition of a republic had to do with its ends, rather than its means. He wrote in Thoughts on Government, "There is no good government but what is republican. That the only valuable part of the British constitution is so; because the very definition of a republic is 'an empire of laws, and not of men.'" Thoughts on Government defended bicameralism, for "a single assembly is liable to all the vices, follies, and frailties of an individual." He also suggested that the executive should be independent, as should the judiciary. Thoughts on Government was enormously influential and was referenced as an authority in every state-constitution writing hall.

On June 7, 1776, Adams seconded the resolution of independence introduced by Richard Henry Lee which stated, "These colonies are, and of right ought to be, free and independent states," and championed the resolution until it was adopted by Congress on July 2, 1776. He was appointed to a committee with Thomas Jefferson, Benjamin Franklin, Robert R. Livingston and Roger Sherman, to draft a Declaration of Independence. Although that document was written primarily by Jefferson, Adams occupied the foremost place in the debate on its adoption. Many years later, Jefferson hailed Adams as "the pillar of [the Declaration's] support on the floor of Congress, its ablest advocate and defender against the multifarious assaults it encountered."

After the defeat of the Continental Army at the Battle of Long Island on August 27, 1776, General William Howe requested the Second Continental Congress send representatives to negotiate peace. A delegation including Adams and Benjamin Franklin met with Howe on Staten Island in New York Harbor on September 11, where Howe demanded the Declaration of Independence be rescinded before any other terms could be discussed. The delegation refused, and hostilities continued. In 1777, Adams resigned his seat on the Massachusetts Superior Court to serve as the head of the Board of War and Ordnance, as well as many other important committees. Congress twice dispatched Adams to represent the fledgling union in Europe, first in 1777, and again in 1779. Accompanied, on both occasions, by his eldest son, John Quincy (who was ten years old at the time of the first voyage), Adams sailed for France aboard the Continental Navy frigate Boston on February 15, 1778. Although chased several times by British warships, the only action seen during the voyage was the bloodless capture of a British privateer. Adams was in some regards an unlikely choice in as much as he did not speak French, the international language of diplomacy at the time.

His first stay in Europe, between April 1, 1778, and June 17, 1779, was largely unproductive, and he returned to his home in Braintree in early August 1779. Between September 1 and October 30, 1779, he drafted the Massachusetts Constitution together with Samuel Adams and James Bowdoin. He was selected in September 1779 to return to France and, following the conclusion of the Massachusetts constitutional convention, left on November 15 aboard the French frigate Sensible.

On the second trip, Adams was appointed as Minister Plenipotentiary charged with the mission of negotiating a treaty of amity and commerce with Britain. The French government, however, did not approve of Adams's appointment and subsequently, on the insistence of the French foreign minister, the Comte de Vergennes, Benjamin Franklin, Thomas Jefferson, John Jay and Henry Laurens were appointed to cooperate with Adams, although Jefferson did not go to Europe and Laurens was posted to the Dutch Republic. In the event Jay, Adams, and Franklin played the major part in the negotiations. Overruling Franklin and distrustful of Vergennes, Jay and Adams decided not to consult with France. Instead, they dealt directly with the British commissioners. Throughout the negotiations, Adams was especially determined that the right of the United States to the fisheries along the Atlantic coast should be recognized. The American negotiators were able to secure a favorable treaty, which gave Americans ownership of all lands east of the Mississippi, except East and West Florida, which were transferred to Spain. The treaty was signed on November 30, 1782.

After these negotiations began, Adams had spent some time as the ambassador in the Dutch Republic, then one of the few other Republics in the world (the Republic of Venice and the Old Swiss Confederacy being the other notable ones). In July 1780, he had been authorized to execute the duties previously assigned to Laurens. With the aid of the Dutch Patriot leader Joan van der Capellen tot den Pol, Adams secured the recognition of the United States as an independent government at The Hague on April 19, 1782. During this visit, he also negotiated a loan of five million guilders financed by Nicolaas van Staphorst and Wilhelm Willink. In October 1782, he negotiated with the Dutch a treaty of amity and commerce, the first such treaty between the United States and a foreign power following the 1778 treaty with France. The house that Adams bought during this stay in The Netherlands became the first American-owned embassy on foreign soil anywhere in the world. For two months during 1783, Adams lodged in London with radical publisher John Stockdale.

In 1784 and 1785, he was one of the architects of far-going trade relations between the US and Prussia. The Prussian ambassador in The Hague, Friedrich Wilhelm von Thulemeyer, was involved, as were Jefferson and Franklin, who were in Paris. In 1785, John Adams was appointed the first American minister to the Court of St. James's (ambassador to Great Britain). When he was presented to his former sovereign, George III, the King intimated that he was aware of Adams's lack of confidence in the French government. Adams admitted this, stating: "I must avow to your Majesty that I have no attachment but to my own country.” Queen Elizabeth II of the United Kingdom referred to this episode on July 7, 1976, at the White House. She said:

John Adams, America's first Ambassador, said to my ancestor, King George III, that it was his desire to help with the restoration of 'the old good nature and the old good humor between our peoples.' That restoration has long been made, and the links of language, tradition, and personal contact have maintained it.

While in London, John and Abigail had to suffer the stares and hostility of the Court, and chose to escape it when they could by seeking out Richard Price, minister of Newington Green Unitarian Church and instigator of the Revolution Controversy. Both admired Price very much, and Abigail took to heart the teachings of the man and his protegee Mary Wollstonecraft, author of A Vindication of the Rights of Woman. Adams's home in England, a house off London's Grosvenor Square, still stands and is commemorated by a plaque. He returned to the United States in 1788 to continue his domestic political life.

Massachusetts's new constitution, ratified in 1780 and written largely by Adams himself, structured its government most closely on his views of politics and society. It was the first constitution written by a special committee and ratified by the people. It was also the first to feature a bicameral legislature, a clear and distinct executive with a partial (two-thirds) veto (although he was restrained by an executive council), and a distinct judicial branch.

While in London, Adams published a work entitled A Defence of the Constitutions of Government of the United States (1787). In it he repudiated the views of Turgot and other European writers as to the viciousness of the framework of state governments. Turgot argued that countries that lacked aristocracies needn't have bicameral legislatures. He thought that republican governments feature “all authorities into one center, that of the nation.” In the book, Adams suggested that "the rich, the well-born and the able" should be set apart from other men in a senate — that would prevent them from dominating the lower house. Wood (2006) has maintained that Adams had become intellectually irrelevant by the time the Federal Constitution was ratified. By then, American political thought, transformed by more than a decade of vigorous and searching debate as well as shaping experiential pressures, had abandoned the classical conception of politics which understood government as a mirror of social estates. Americans' new conception of popular sovereignty now saw the people-at-large as the sole possessors of power in the realm. All agents of the government enjoyed mere portions of the people's power and only for a limited time. Adams had completely missed this concept and revealed his continued attachment to the older version of politics. Yet Wood overlooks Adams's peculiar definition of the term "republic," and his support for a constitution ratified by the people. He also underplays Adams's belief in checks and balances. "Power must be opposed to power, and interest to interest,” Adams wrote; this sentiment would later be echoed by James Madison's famous statement that "[a]mbition must be made to counteract ambition" in The Federalist No. 51, in explaining the powers of the branches of the United States federal government under the new Constitution. Adams did as much as anyone to put the idea of "checks and balances" on the intellectual map.

Adams never bought a slave and declined on principle to employ slave labor. Abigail Adams opposed slavery and employed free blacks in preference to her father's two domestic slaves. He spoke out against a bill to emancipate slaves in Massachusetts, opposed use of black soldiers in the Revolution, and tried to keep the issue out of national politics.

While Washington won unanimously in the popular vote and won 69 votes in the electoral college, Adams came in second in the electoral college with 34 votes and became Vice President in the presidential election of 1789. He presided over the Senate but otherwise played a minor role in the politics of the early 1790s; he was reelected in 1792. Washington seldom asked Adams for input on policy and legal issues during his tenure as vice president. In the first year of Washington's administration, Adams became deeply involved in a month-long Senate controversy over the official title of the President. Adams favored grandiose titles such as "His Majesty the President" or "His High Mightiness" over the simple "President of the United States" that eventually won the debate. The pomposity of his stance, along with his being overweight, led to Adams earning the nickname "His Rotundity."

As president of the Senate, Adams cast 29 tie-breaking votes — a record that only John C. Calhoun came close to tying, with 28. His votes protected the president's sole authority over the removal of appointees and influenced the location of the national capital. On at least one occasion, he persuaded senators to vote against legislation that he opposed, and he frequently lectured the Senate on procedural and policy matters. Adams's political views and his active role in the Senate made him a natural target for critics of the Washington administration. Toward the end of his first term, as a result of a threatened resolution that would have silenced him except for procedural and policy matters, he began to exercise more restraint. When the two political parties formed, he joined the Federalist Party, but never got on well with its dominant leader Alexander Hamilton. Because of Adams's seniority and the need for a northern president, he was elected as the Federalist nominee for president in 1796, over Thomas Jefferson, the leader of the opposition Democratic-Republican Party. His success was due to peace and prosperity; Washington and Hamilton had averted war with Britain with the Jay Treaty of 1795. Adams's two terms as Vice President were frustrating experiences for a man of his vigor, intellect, and vanity. He complained to his wife Abigail, "My country has in its wisdom contrived for me the most insignificant office that ever the invention of man contrived or his imagination conceived."

The 1796 election was the first contested election under the First Party System. Adams was the presidential candidate of the Federalist Party and Thomas Pinckney, the Governor of South Carolina, was also running as a Federalist (at this point, the vice president was whoever came in second, so no running mates existed in the modern sense). The Federalists wanted Adams as their presidential candidate to crush Thomas Jefferson's bid. Most Federalists would have preferred Hamilton to be a candidate. Although Hamilton and his followers supported Adams, they also held a grudge against him. They did consider him to be the lesser of the two evils. However, they thought Adams lacked the seriousness and popularity that had caused Washington to be successful and feared that Adams was too vain, opinionated, unpredictable, and stubborn to follow their directions. Adams's opponents were former Secretary of State Thomas Jefferson of Virginia, who was joined by Senator Aaron Burr of New Yorkon the Democratic-Republican ticket. As was customary, Adams stayed in his home town of Quincy rather than actively campaign for the Presidency. He wanted to stay out of what he called the silly and wicked game. His party, however, campaigned for him, while the Democratic-Republicans campaigned for Jefferson. It was expected that Adams would dominate the votes in New England, while Jefferson was expected to win in the Southern states. In the end, Adams won the election by a narrow margin of 71 electoral votes to 68 for Jefferson (who became the vice president).

As President Adams followed Washington's lead in making the presidency the example of republican values, and stressing civic virtue; he was never implicated in any scandal. Some historians consider his worst mistake to be keeping the old cabinet, which was controlled by Hamilton, instead of installing his own people, confirming Adams' own admission that he was a poor politician because he "was unpractised in intrigues for power." Yet, there are those historians who feel that Adams' retention of Washington's cabinet was a statesmanlike step to soothe worries about an orderly succession. As Adams himself explained, "I had then no particular object of any of them." Adams spent much of his term at his home Massachusetts, ignoring the details of patronage and communication that were not ignored by his opponents in both parties. Adams' combative spirit did not always lend itself to presidential decorum, as Adams himself admitted in his old age: "[As president] I refused to suffer in silence. I sighed, sobbed, and groaned, and sometimes screeched and screamed. And I must confess to my shame and sorrow that I sometimes swore."

Adams continued not just the Washington cabinet but all the major programs of the Washington Administration as well. Adams made no major new proposals. His economic programs were thus a continuation of those of Hamilton, who regularly consulted with key cabinet members, especially the powerful Secretary of the Treasury, Oliver Wolcott, Jr.

Adams's term (1797–1801) was marked by intense disputes over foreign policy and a limited naval war with France. Britain and France were at war; Hamilton and the Federalists favored Britain, while Jefferson and the Democratic-Republicans favored France. When Adams entered office, he realized that he needed to protect Washington’s policy of staying out of the French and British war. Indeed, the intense battle over the Jay Treaty in 1795 permanently polarized politics up and down the nation, marking the start of the First Party System, with most elections now contested. The French saw America as Britain's junior partner and began seizing American merchant ships that were trading with the British in what became known as the "Quasi-War." Neither nation declared war officially, but the risk was high and the Federalists re-armed the nation in preparation for war — and perhaps in preparation for suppressing the anti-war Republicans.

The humiliation of the XYZ Affair, in which the French demanded huge bribes before any discussions could begin, led to serious threats of full-scale war with France and embarrassed the Jeffersonians, who were friends to France. An undeclared naval war between the U.S. and France, called the Quasi-War, broke out in 1798, and there was danger of invasion from the much larger and more powerful French forces. The Federalists built up the army, bringing back Washington as its head and Hamilton as its leading force. Adams rebuilt the Navy, adding six fast, powerful frigates, such as USS Constitution. To pay for it all, Congress raised taxes.

Federalists in Congress passed the Alien and Sedition Acts, which were signed by Adams in 1798. There were four separate acts:

• The Naturalization Act, passed on June 18
• The Alien Act, passed on June 24
• The Alien Enemies Act, passed on July 6
• The Sedition Act, passed on July 14

These four acts were passed to suppress Republican opposition. The Naturalization Act changed the period of residence required before an immigrant could attain American citizenship to 14 years (naturalized citizens tended to vote for the Democratic-Republicans). The Alien Friends Act and the Alien Enemies Act allowed the president to deport any foreigner he thought dangerous to the country. The Sedition Act made it a crime to publish "false, scandalous, and malicious writing" against the government or its officials. Punishments included 2–5 years in prison and fines of up to $5,000. Although Adams had not originated or promoted any of these acts, he nevertheless signed them into law. Those acts, and the high-profile prosecution of a number of newspaper editors and one member of Congress by the Federalists, became highly controversial. Some historians have noted that the Alien and Sedition Acts were relatively rarely enforced, as only 10 convictions under the Sedition Act have been identified and as Adams never signed a deportation order, and that the furor over the Alien and Sedition Acts was mainly stirred up by the Democratic-Republicans. However, other historians emphasize that the Acts were highly controversial from the outset, resulting in many aliens leaving the country voluntarily, and created an atmosphere where opposing the Federalists, even on the floor of Congress, could and did result in prosecution.

The election of 1800 became a bitter and volatile battle, with each side expressing extraordinary fear of the other party and its policies. The Federalist party was deeply divided over the leadership of the Army. Adams was forced to name Washington as commander of the new army, and Washington demanded that Hamilton be his second-in-command. Adams reluctantly gave in. Major General Hamilton assumed a high degree of control over the War department. The rift between Adams and the High Federalists (as Adams's opponents were called) grew wider. The High Federalists refused to consult Adams over the key legislation of 1798; they changed the defense measures which he had called for, demanded that Hamilton control the army, and refused to recognize the necessity of giving key Democratic-Republicans (like Aaron Burr) senior positions in the army (which Adams wanted to do to gain some Democratic-Republican support). By building a large standing army the High Federalists raised popular alarms and played into the hands of the Democratic-Republicans. They also alienated Adams and his large personal following. They shortsightedly viewed the Federalist party as their own tool and ignored the need to pull together the entire nation in the face of war with France.

For long stretches, Adams withdrew to his home in Massachusetts. In February 1799, Adams stunned the country by sending diplomat William Vans Murray on a peace mission to France. Napoleon, realizing the animosity of the United States was doing no good, signaled his readiness for friendly relations. The Treaty of Alliance of 1778 was superseded and the United States could now be free of foreign entanglements, as Washington advised in his own Farewell Letter. Adams avoided war, but deeply split his own party in the process. He brought in John Marshall as Secretary of State and demobilized the emergency army.

To pay for the new Army, Congress imposed new taxes on property: the Direct Tax of 1798. It was the first (and last) such federal tax. Taxpayers were angry, nowhere more so that in southeast Pennsylvania, where the bloodless Fries' Rebellion broke out among rural German-speaking farmers who protested what they saw as a threat to their republican liberties and to their churches.

The death of Washington, in 1799, weakened the Federalists, as they lost the one man who symbolized and united the party. In the presidential election of 1800, Adams and his fellow Federalist candidate, Charles Cotesworth Pinckney, went against the Republican duo of Jefferson and Burr. Hamilton tried his hardest to sabotage Adams's campaign in hopes of boosting Pinckney's chances of winning the presidency. In the end, Adams lost narrowly to Jefferson by 65 to 73 electoral votes, with New York casting the decisive vote. Adams was defeated because of better organization by the Republicans and Federalist disunity; by the popular disapproval of the Alien and Sedition Acts, the popularity of his opponent, Jefferson, and the effective politicking of Aaron Burr in New York State, where the legislature (which selected the electoral college) shifted from Federalist to Democratic-Republican on the basis of a few wards in New York City controlled by Burr's machine.

In the closing months of his term Adams became the first President to occupy the new, but unfinished President's Mansion, beginning November 1, 1800.

The lame-duck session of Congress enacted the Judiciary Act of 1801, which created a set of federal appeals courts between the district courts and the Supreme Court. As his term was expiring, Adams filled the vacancies created by this statute by appointing a series of judges, called the "Midnight Judges" because most of them were formally appointed days before the presidential term expired. Most of the judges were eventually unseated when the Jeffersonians enacted the Judiciary Act of 1802, abolishing the courts created by the Judiciary Act of 1801 and returning the structure of the federal courts to what it had been before the 1801 statute. Adams's greatest legacy was his naming of John Marshall as the fourth Chief Justice of the United States to succeed Oliver Ellsworth, who had retired due to ill health. Marshall's long tenure represents the most lasting influence of the Federalists, as Marshall infused the Constitution with a judicious and carefully reasoned nationalistic interpretation and established the Judicial Branch as the equal of the Executive and Legislative branches.

Following his 1800 defeat, Adams retired into private life. Depressed when he left office, he did not attend Jefferson's inauguration, making him one of only four surviving presidents (i.e., those who did not die in office) not to attend his successor's inauguration. Adams's correspondence with Jefferson at the time of the transition suggests that he did not feel the animosity or resentment that later scholars have attributed to him. He left Washington before Jefferson's inauguration as much out of sorrow at the death of his son Charles Adams (due in part to the younger man's alcoholism) and his desire to rejoin his wife Abigail, who had left for Massachusetts months before the inauguration. Adams resumed farming at his home, Peacefield, near the town of Quincy, which had absorbed his birthplace, Braintree. He began to work on an autobiography (which he never finished), and resumed correspondence with such old friends as Benjamin Waterhouse and Benjamin Rush. He also began a bitter and resentful correspondence with an old family friend, Mercy Otis Warren, protesting how in her 1805 history of the American Revolution she had, in his view, caricatured his political beliefs and misrepresented his services to the country.

After Jefferson's retirement from public life in 1809 after two terms as President, Adams became more vocal. For three years he published a stream of letters in the Boston Patriot newspaper, presenting a long and almost line-by-line refutation of an 1800 pamphlet by Hamilton attacking his conduct and character. Though Hamilton had died in 1804 from a mortal wound sustained in his notorious duel with Aaron Burr, Adams felt the need to vindicate his character against the New Yorker's vehement attacks.

In early 1812, Adams reconciled with Jefferson. Their mutual friend Benjamin Rush, a fellow signer of the Declaration of Independence who had been corresponding with both, encouraged each man to reach out to the other. On New Year's Day 1812, Adams sent a brief, friendly note to Jefferson to accompany the delivery of "two pieces of homespun," a two-volume collection of lectures on rhetoric by John Quincy Adams. Jefferson replied immediately with a warm, friendly letter, and the two men revived their friendship, which they conducted by mail. The correspondence that they resumed in 1812 lasted the rest of their lives, and thereafter has been hailed as one of their greatest legacies and a monument of American literature. Their letters are rich in insight into both the period and the minds of the two Presidents and revolutionary leaders. Their correspondence lasted fourteen years, and consisted of 158 letters. It was in these years that the two men discussed "natural aristocracy." Jefferson said, "The natural aristocracy I consider as the most precious gift of nature for the instruction, the trusts, and government of society. And indeed it would have been inconsistent in creation to have formed man for the social state, and not to have provided virtue and wisdom enough to manage the concerns of society. May we not even say that the form of government is best which provides most effectually for a pure selection of these natural aristoi into the offices of government?" Adams wondered if it ever would be so clear who these people were, "Your distinction between natural and artificial aristocracy does not appear to me well founded. Birth and wealth are conferred on some men as imperiously by nature, as genius, strength, or beauty. . . . When aristocracies are established by human laws and honour, wealth, and power are made hereditary by municipal laws and political institutions, then I acknowledge artificial aristocracy to commence." It would always be true, Adams argued, that fate would bestow influence on some men for reasons other than true wisdom and virtue. That being the way of nature, he thought such "talents" were natural. A good government, therefore, had to account for that reality.

Sixteen months before John Adams's death, his son, John Quincy Adams, became the sixth President of the United States (1825 – 1829), the only son of a former President to hold the office until George W. Bush in 2001.

Adams's daughter Abigail ("Nabby") was married to Representative William Stephens Smith, but she returned to her parents' home after the failure of her marriage. She died of breast cancer in 1813. His son Charles died as an alcoholic in 1800. Abigail, his wife, died of typhoid on October 28, 1818. His son Thomas and his family lived with Adams and Louisa Smith (Abigail's niece by her brother William) to the end of Adams's life.

Less than a month before his death, John Adams issued a statement about the destiny of the United States, which historians such as Joy Hakim have characterized as a "warning" for his fellow citizens. Adams said:

My best wishes, in the joys, and festivities, and the solemn services of that day on which will be completed the fiftieth year from its birth, of the independence of the United States: a memorable epoch in the annals of the human race, destined in future history to form the brightest or the blackest page, according to the use or the abuse of those political institutions by which they shall, in time to come, be shaped by the human mind.

On July 4, 1826, the fiftieth anniversary of the adoption of the Declaration of Independence, Adams died at his home in Quincy. Told that it was the Fourth, he answered clearly, "It is a great day. It is a good day." His last words have been reported as "Thomas Jefferson survives". Only the first two words "Thomas Jefferson" were clearly intelligible, however. Adams was unaware that Jefferson, his compatriot in their quest for independence, then great political rival, then later friend and correspondent, had died a few hours earlier on the very same day. Somewhat later, struggling for breath, he whispered to his granddaughter Susanna, "Help me, child! Help me!" then lapsed into a final silence. At about 6:20, John Adams was dead, leaving Charles Carroll of Carrollton as the last surviving signatory of the Declaration of Independence. He died while John Quincy Adams was president.

His crypt lies at United First Parish Church (also known as the Church of the Presidents) in Quincy. Originally, he was buried in Hancock Cemetery, across the road from the Church. Until his record was broken by Ronald Reagan in 2001, he was the nation's longest-living President (90 years, 247 days) maintaining that record for 175 years. The record is currently held by former President Gerald Ford who died on December 26th, 2006, at age 93 years, 165 days.