1778: Treaty of Alliance with France, engineered by Benjamin Franklin, enabled the fledgling republic to continue its struggle for independence.
1783: Treaty of Paris-Great Britain recognized American independence and control over western lands as far as the Mississippi.
1795: Jay's Treaty required Great Britain to remove troops from northwestern frontier; Pinckney's Treaty with Spain opened mouth of Mississippi River to U.S. navigation.
1803: Louisiana Purchase removed foreign control of Mississippi's mouth and doubled U.S. territory.
1819: Adams-Onis Treaty with Spain, transferring Florida, extended the U.S. to present boundaries in southeast.
1823: Monroe Doctrine established U.S. policy of opposing European intervention or new colonization in Western Hemisphere.
1842: Webster-Ashburton Treaty with Great Britain delimited northeastern U.S. (Maine) boundary.
1846: Oregon Treaty with Great Britain extended U.S. sole dominion to the Pacific.
1848: Treaty of Guadalupe-Hidalgo, ending 1846-48 war with Mexico, confirmed U.S. claim to Texas and completed U.S. expansion to Pacific.
1867: Alaska purchase ended Russian territorial presence and completed U.S. expansion on North American mainland.
1898: Treaty of Paris, at end of Spanish-American War, transferred to the United States Puerto Rico, Guam, and the Philippines, expanding U.S. power into the Pacific.
1918: Allies and Germany accepted Wilson's 14 points as basis for just and lasting peace ending World War I.
1945: U.S. and 50 other countries founded the United Nations.
1947: Truman Doctrine asserted U.S. policy of containing Soviet expansion through economic and military aid to threatened countries.
1947: Marshall plan of aid to Europe set foundation for economic cooperation among industrial democracies.
1948: Ninth International Conference of American States created the Organization of American States (OAS) to intensify U.S. and Latin American collaboration in all fields.
1948: NATO, first U.S. alliance concluded in peacetime, provided integrated force for defense of Western Europe and North America.
1963: Limited Nuclear Test Ban Treaty, first major-power agreement regulating atomic weapons testing, banned explosions in the atmosphere, in outer space and under water.
1967: Nonproliferation Treaty, now signed by 110 governments, banned the spread of atomic weapons.
1972: Strategic Arms Limitation Talks (SALT) agreements with U.S.S.R. prescribed mutual limitations on defensive and offensive weapons and established SALT as a continuing process.
1972: President Nixon's February visit to China followed Secretary Kissinger's earlier negotiations in Peking, marking first important step in the process of normalizing relations with the People's Republic of China.
1979: U.S. established diplomatic relations with the People's Republic of China ending 30 years of nonrecognition.
1979: Israel-Egypt Peace Treaty (Camp David Accords) ended 30 years of conflict between the two countries and provided possible framework for comprehensive peace in the Middle East.
1986: The U.S. Congress implemented strong economic sanctions against South Africa, which helped to bring an end to apartheid in 1991.
1989-1991: As President George H.W. Bush stated a desire to integrate the Soviet Union into the community of nations, the Cold War ended when communist regimes collapsed across Eastern Europe and the Soviet Union disintegrated.
1990-1991: In response to the Iraqi invasion of Kuwait, the United States built an international coalition to defend Saudi Arabia and, after United Nations approval, to eject Iraq from Kuwait through Operation Desert Storm.
1992: Representatives of more than 175 nations, including the United States, met at the Earth Summit in Rio de Janeiro, which produced a treaty on climate change and was the largest international meeting on the environment ever convened.
1994: The North American Free Trade Agreement (NAFTA) between the United States, Canada, and Mexico took effect and the United States joined another structure that promoted global free trade, the World Trade Organization.
1995: The General Framework Agreement for Peace in Bosnia and Herzegovina ended the Bosnian civil war by providing for NATO troops to serve as peacekeepers.
2001: The United States led a global coalition that fought a war against terrorism in the wake of the September 11 terrorist attacks in New York and Washington D.C.
2003: After Iraq's repeated refusals to comply with UN resolutions, the United States led a coalition to depose the regime of Saddam Hussein.