Costs of Major U.S. Wars (All dollars in billions; source: Congressional Research Service)

War
Current (Then Year) Dollars
Constant (FY 2007) Dollars

American Revolution
$ 0.12
$ 3.577

War of 1812
$ 0.89
$ 1.126

Mexican War
$ 0.82
$ 1.987

Civil War (US)
$ 2.30
$ 56.297

Civil War (CSA)
$ 1.0
$ 24.506

Spanish-American War
$ 0.27
$ 7.286

World War I
$ 33.0
$ 642.0

World War II
$ 296.0
$ 3,211.0

Korea
$ 67.0
$ 691.0

Vietnam
$ 111.0
$ 650.0

Desert Storm
$ 61.0
$ 92.0

Global War On Terrorism
n/a
$439.0

The current war is now the fifth most expensive in U.S. history (behind World War I, World War II, the Korean War, and the Vietnam War). If the Congressional Budget Office correctly projects 2007 to 2016 GWOT costs at $371 billion, the current war’s total becomes $810 billion, which would make it America’s second most expensive war (second only to World War II).
Click here to see the CRS table, as distributed on Capitol Hill.