For many Americans, the Memorial Day holiday marks the unofficial start to summer, as children look forward to the end of the school year, people make vacation plans, and merchants make sales pitches. However, the holiday has a more profound meaning. Memorial Day honors those men and women in the armed forces who gave their lives in the service of the United States.

While any human toll in armed conflict is grave and as such immeasurable, wars also cost money.

Many factors can affect the cost of waging war. Using a report from the Congressional Research Service, 24/7 Wall St. reviewed the most expensive wars in U.S. history. To determine the most expensive wars in U.S. history, 24/7 Wall St. used a 2010 report from the Congressional Research Service titled, “Costs of Major U.S. Wars.” The report does not include veterans’ benefits, interest on loans used to finance the war, and assistance to allies. Spending figures were inflation-adjusted to 2011 dollars.

Click here to see the most expensive wars in U.S. history.
Click here to see our detailed findings and methodology.