Presidential electors, meeting in their state capitals, cast their ballots for president and vice president of the United States.
John Adams, serving out the last months of his presidency, nominates John Marshall to the United States Supreme Court.
When Electoral College ballots are tallied, the perplexing result is a tie between the Republican candidate for president, Thomas Jefferson, and his running mate, Republican vice-presidential nominee Aaron Burr. The election is therefore thrown into the House of Representatives as prescribed by the Constitution.
The Federalist-dominated Congress passes the Judiciary Act, creating sixteen new circuit courts and thus providing President Adams with the opportunity to appoint sixteen new judges and dozens of federal attorneys, clerks, and justices of the peace in the final days of his presidency. The act also reduces the number of Supreme Court justices to five.
Thomas Jefferson is elected president by the House of Representatives on the 36th ballot. Aaron Burr is elected vice-president.
Thomas Jefferson is inaugurated president of the United States. He becomes the first president to be inaugurated in the new capital of Washington City.
The Republican-dominated Congress repeals the Judiciary Act of 1801. Congress's repeal will be challenged by Federalists but ultimately upheld by the Supreme Court in 1803.
The United States Military Academy at West Point, founded by an act of Congress, opens and begins training officer cadets.
James Callender publishes allegations in the Richmond Recorder that Thomas Jefferson has "for many years past kept, as his concubine, one of his slaves."
Thomas Jefferson submits a request to Congress for funding for an expedition to explore the Mississippi River and western territories.
The Supreme Court issues its ruling in the case of Marbury v. Madison, one of the most momentous court decisions in American history. Writing the majority opinion, Chief Justice John Marshall argues that the Court lacks the authority to issue the writ of mandamus requested by William Marbury, which would have ordered Secretary of State James Madison to deliver his letter of appointment as justice of the peace for the city of Washington. Congress had granted the authority to issue these writs in the Judiciary Act of 1789, but the Court rules that Congress exceeded its Constitutional authority when it did so. In striking down the relevant section of the 1789 Judiciary Act, the Court asserts the principle of judicial review: the power of the Court to rule on the constitutionality of congressional actions.
The United States Senate approves the treaty signed earlier with France to purchase the Louisiana Territory. Jefferson has questioned the constitutionality of the treaty, which adds 828,000 square miles to the United States, doubling its size. But fearing that France might renege under Spanish pressure if given the chance by American delay, he ultimately supports prompt ratification.
Federal District Judge John Pickering, having been impeached by the House, is judged guilty under provisions of the Constitution and removed from the bench. Pickering's impeachment is a victory for a Republican-dominated Congress anxious to assert the power of the legislative against the judicial branch.
The Lewis and Clark expedition leaves Fort DuBois, Illinois, beginning its long overland journey to the Pacific coast.
Former Secretary of the Treasury Alexander Hamilton and current Vice-President of the United States Aaron Burr, longtime political rivals, fight each other in a duel at Weehawken, New Jersey. Hamilton is fatally wounded.
Thomas Jefferson is elected to a second term of office, defeating his Federalist opponent in a 162-14 landslide in the Electoral College. In a separate ballot—mandated by the Twelfth Amendment, ratified in 1804 in response to the Jefferson-Burr tie of 1800—Republican George Clinton is elected vice-president.
A British Court condemns the American merchant ship Essex for violating British maritime policies. The Essex had been carrying a cargo picked up in Martinique—a possession of Britain's enemy, France. The decision signals the end of Britain's recognition of American rights as a neutral carrier—that is, the right, as a neutral nation, to carry the goods of both warring countries without interference. Within weeks, dozens of American ships are seized by the British navy.
The Battle of Trafalgar, one of the most consequential naval battles in world history, is fought off the coast of Spain. The British Royal Navy defeats the combined fleets of Spain and France, securing British control of the Atlantic for the next century.
President Thomas Jefferson issues a proclamation condemning the conspiracy of Aaron Burr. He first heard allegations that Burr, his former vice president, had launched some sort of plot in the southwest in February 1806, but initially he did not act upon this information because he believed the charges were fabricated by his political enemies. Finally convinced that Burr is engaged in some sort of conspiracy to break off the southwestern territories in order to form a separate confederacy, he labels the plot a "criminal enterprise" and urges federal authorities to apprehend the conspirators.
American envoys James Monroe and William Pinkney negotiate a treaty with Great Britain in an attempt to improve trade and diminish maritime tensions between the two nations. The United States seeks commercial access to British markets in the West Indies and the revision of British policies on neutral shipping and impressment. While Britain makes some concessions on trade, it refuses to relinquish the right to stop foreign vessels and search their crews for deserters from the British navy. Jefferson therefore will find the terms of the Monroe-Pinkney Treaty unacceptable and will refuse to submit it to the Senate for approval.
Aaron Burr is captured near New Orleans. He will be accused of conspiring to start a revolution aimed at secession in the southwest and charged with treason. But the government's case against Burr is weak, and it is hindered by a narrow definition of treason issued by Chief Justice John Marshall who presides over the circuit court that hears Burr's case. Burr will be acquitted on 1 September 1807.
The USS Chesapeake, sailing off the Virginia coast, is fired upon by the Leopard, a British ship of war, after the Chesapeake's commander refuses to allow the British to board his ship to search for British naval deserters. The American public is outraged by the event and President Jefferson orders all British ships out of American territorial waters.
Congress passes an embargo against all foreign commerce, restricting American ships to sail to American ports only. Foreign vessels will be permitted to deliver, but not pick up, cargoes in American ports. Through this embargo Jefferson hopes to prevent war with Britain and, by applying economic pressure, convince Britain to revise its maritime policies.
Congressional legislation (passed on 2 March 1807) forbidding further importation of slaves into the United States goes into effect. The Constitution as written in 1789 had prohibited Congress from interfering with the importation of slaves until 1808; Congress thus bans the trade on the earliest possible day. By this time, all states but South Carolina have already taken action against the importation of slaves from foreign ports.
As evasion of his trade embargo increases, Jefferson declares Lake Champlain, the main route by which goods are being smuggled to Canada, to be in a state of insurrection.
The Electoral College selects James Madison as the fourth president of the United States. Madison receives 122 votes; Federalist candidate Charles Cotesworth Pinckney receives 47. George Clinton, a second Republican candidate representing a northern branch of the party, receives 6 votes. Clinton also receives a majority of the second ballots and is elected vice-president.
At President Jefferson's request, Congress passes an Enforcement Act increasing his authority to intercept and seize cargoes suspected to be in violation of the embargo.
Thomas Jefferson signs the Non-Intercourse Act passed by Congress to replace the embargo passed in December 1807. This new act legalizes trade with all nations except Great Britain and France, and authorizes the president to re-open trade with either or both of those countries if they revise their maritime policies and recognize American claims to neutral shipping rights.
James Madison is inaugurated as the fourth president of the United States. Jefferson leaves the very same day for his beloved estate Monticello; he will never again return to Washington or leave Virginia.