How many wars have been fought by the United States?

This would depend upon the definition of "war" (declared or undeclared), but major military actions by US armed forces are seen as wars. Shorter actions are characterized as "engagements."

Wars including colonial or United States forces

The French and Indian War, the Revolutionary War, the War of 1812, the Mexican-American War, the Civil War, World War I, and World War II were authorized by colonial leaders or Congress. The Vietnam War, the Gulf War, the War in Afghanistan (2001), and the War on Iraq (2003) were military engagements authorized by Congress and have become commonly known as "wars."

The Korean War (1950-1953 armistice) was a "Military Engagement" that was authorized by the United Nations Security Council.

Major Wars by the United States in chronological order

• French and Indian War (1754-1763) colonial militias
• American Revolution (1775-1783)
• War of 1812 (1812-1814)
• Mexican-American War (1846-1848)
• US Civil War (1861-1865)
• Spanish-American War (1898)
• World War 1 (1914-1918) entered 1917
• World War 2 (1939-1945) entered 1941
• Korean War (1950-1953*) (*not over, but fighting ceased)
• Vietnam War (1964-1975) advisers sent beginning 1955
• Gulf War (1991)
• War in Afghanistan (2001-present) supported tribal war against Taliban
• Iraq War (2003-present) Iraq regime overthrown 2003

Other notable actions : Quasi-War with France (1800), American Indian Wars (1800-1910, most heavily 1860-1880), Phillippine Insurrection (1899-1902), Grenada invasion (1983), Panama invasion (1989)