Timeline of United States diplomatic history

The diplomatic history of the United States oscillated among three positions: isolation from diplomatic entanglements of other (typically European) nations (but with economic connections to the world); alliances with European and other military partners; and unilateralism, or operating on its own sovereign policy decisions. The US always was large in terms of area, but its population was small, only 4 million in 1790. Population growth was rapid, reaching 7.2 million in 1810, 32 million in 1860, 76 million in 1900, 132 million in 1940, and 316 million in 2013. Economic growth in terms of overall GDP was even faster. However, the nation's military strength was quite limited in peacetime before 1940.
Brune (2003) and Arthur M. Schlesinger, Jr., ed. "The Almanac of American History" (1983) have specifics for many incidents.
19th century.
 The beginning of the First Barbary War. President Jefferson does not ask Congress for a declaration of war against Tripoli, but instead decides to begin military operations against Tripoli, arguing that the President has the right to begin military operations in self-defense without asking for permission from Congress.
1802 –
1945–2000.
1955
1974–