March 4, 1797: John Adams Inaugurated Adams succeeds George Washington and becomes the second president of the United States after a tight election. Thomas Jefferson, the runner-up, becomes vice president.
October 1797: The XYZ Affair French foreign minister Charles de Tallyrand refuses to meet with an American diplomatic envoy unless paid $250,000 for himself and guaranteed a $12 million loan for France. The American public is outraged.
June - July 1798: Alien and Sedition Acts Passed Adams signs the four measures that make up the Alien and Sedition Acts into law, rousing staunch opposition from Republicans and even some Federalists. The Alien and Sedition Acts represent the height of Federalist expansion of the powers of national government.
November - December 1798: Kentucky and Virginia Resolutions are Adopted Kentucky and Virginia adopt resolutions, written anonymously by Thomas Jefferson and James Madison, which affirm the doctrine of states' rights over the national government, and assert that states maintain the power of interposition, allowing them to review the constitutionality of congressional measures.
October 1, 1800: Treaty of San Ildefonso Signed The Treaty of San Ildefonso, signed by France and Spain, grants France ownership of the Louisiana Territory.
February 27, 1801: The Judiciary Act of 1801 is Passed The Judiciary Act of 1801 is passed, creating sixteen new federal judgeships and reducing the number of Supreme Court justices from six to five, robbing Jefferson of his first appointment.
March 4, 1801: Thomas Jefferson Inaugurated After a Republican victory in the election of 1800, Jefferson becomes the nation's third president.
February 1803: John Marshall Delivers his Decision in Marbury v. Madison Supreme Court Chief Justice Marshall decrees that the Judiciary Act of 1789 is unconstitutional in its affirmation of the right of the Supreme Court to issue a writ of mandamus. This decision established the Supreme Court's power of judicial review.
December 20, 1803: US Takes Possession of Louisiana Eight months after the Louisiana Purchase is negotiated in April, the US takes formal possession of the new territory, doubling the nation's size.
May 1804: Lewis and Clark Set Out Off from St. Louis After preparing over the winter, the famous expedition, led by Meriwether Lewis and William Clark begins north on the Missouri River with a team of 45 military personnel.
November 7, 1805: Lewis and Clark Reach The Pacific Ocean Convention Having traveled over the mountains in southern Idaho and down the Snake and Columbia Rivers, the expedition reaches the mouth of the Columbia, on the Pacific Ocean, where they spend their second winter.
September 1806: Lewis and Clark Return to St. Louis The expedition returns intact to St. Louis, having traveled 3,000 miles in just two and a half years, an unprecedented feat. Their return prompts great interest in the west.
June 22, 1807: The Chesapeake-Leopard Affair The British naval frigate HMS Leopard follows the American naval frigate USS Chesapeake out of Norfolk harbor in Virginia, and opens fire upon it after a request to board is denied. The Chesapeake, not prepared for battle, loses three men and has twenty wounded, and permits the British to board. The British naval officers board, seize four men who had deserted the royal navy, hang them from a yardarm, and sail away.
September 1, 1807: Aaron Burr Acquitted of Treason After his planned conspiracy to attack Texas and secede from the Union fails, Burr is captured and tried for treason. Chief Justice Marshall rules that the inoperative intent to divide the Union does not constitute treason, and Burr is acquitted.
December 22, 1807: The Embargo Act is Passed In response to the Chesapeake-Leopard Affair, Jefferson advocates the Embargo Act, which forbids ships to leave from American ports for trade with foreign ports. He intends the embargo to work as peaceable coercion, forcing the British and French to respect American neutrality at sea.
March 3, 1809: The Embargo Act is Repealed After over a year of economic suffering in the United States, and the rise of vocal public criticism of the Embargo Act, the act is repealed, and replaced with a tamer non-intercourse law regarding France and Britain.
March 4, 1809: James Madison Inaugurated Though the nation was disappointed with Jefferson's final major action in office, the Embargo Act, the Republicans remained the majority party, and James Madison easily won the 1808 election, becoming the nation's fourth president in 1809.