How Long Every War in U.S. History Actually Lasted and What It Cost

The table below is the most comprehensive comparison of every major U.S. war ever compiled in one place. Costs are shown in both original-year dollars and inflation-adjusted to approximately 2025 dollars. The "Total Cost" column for pre-WWII wars uses CRS military-operations-only figures. The War on Terror figures use Brown University's broader methodology, which includes veterans' care, homeland security, and interest on war borrowing - a more honest accounting of what these wars actually cost American taxpayers.

When you put every American war on a single chart, two conflicts tower above everything else: World War II at roughly $4.7 trillion and the War on Terror at $8 trillion and counting. The War on Terror's staggering price tag becomes even more remarkable when you consider that at no point did defense spending exceed 5% of GDP - compared to WWII's 40%. The difference is duration: fighting a global war for 20+ years on a credit card adds up.

The next most expensive conflict is Vietnam at roughly $950 billion, followed by Korea and WWI at about $440 billion each. Every other war in American history - including the Civil War, the Mexican-American War, the War of 1812, and the Revolution - cost less than the U.S. currently spends on its military in a single year.

The Civil War remains the deadliest conflict in American history by an enormous margin. Newer research by historian J. David Hacker suggests the true death toll may be as high as 750,000 - more than all other American wars combined. At its bloodiest, the Civil War was killing an average of 425 Americans per day, a rate that dwarfs any other conflict. For comparison, WWII averaged about 297 deaths per day, WWI about 199, and Korea about 32.

The post-9/11 wars represent a dramatic shift in the ratio of dollars to lives. The Gulf War cost $347 million per American death. Afghanistan cost $935 million per death. The entire War on Terror has cost over $1.13 billion for every American service member killed - a reflection of both the astonishing expense of modern warfare and dramatic improvements in battlefield medicine that have saved thousands of lives that would have been lost in earlier eras.

The Afghanistan War (October 2001 to August 2021) holds the title of America's longest war at 7,267 days, just edging out the full span of U.S. involvement in Vietnam (November 1955 to April 1975, 7,121 days). But the character of the fighting was vastly different: Vietnam saw peak troop deployments of 543,000 with an average of 19 deaths per day during the combat years (1964-1973), while Afghanistan rarely exceeded 100,000 troops and averaged less than one death per day over its full duration.

At the other extreme, the Spanish-American War lasted just 109 days and the Gulf War's combat phase was only 42 days (though the full deployment lasted about 7 months). The trend is clear: modern American wars are getting longer while getting less lethal for U.S. troops - but far more expensive.

Perhaps the most telling way to measure a war's true burden is its cost as a share of GDP. By this measure, the early wars were devastating: the Revolution consumed roughly 63% of colonial economic output at its peak (though early GDP estimates are extremely rough), and the Civil War hit 24%. But WWII holds the modern record at a staggering 40% of GDP devoted to defense in 1945.

The War on Terror, despite its $8 trillion price tag, never exceeded about 5% of GDP in any single year. This doesn't mean it was affordable - it means it was financed entirely through debt rather than through taxes or war bonds as in previous conflicts. By 2030, Brown University estimates that interest payments alone on War on Terror borrowing will exceed $2 trillion - more than the entire direct cost of fighting in Afghanistan.

One of the most striking trends in American warfare is the skyrocketing cost per U.S. death. In the Revolution, each American death "cost" about $128,000 in today's money. By WWII, it was $11.6 million. The Gulf War - with only 383 combat deaths against a $133 billion campaign - hit $347 million per death. And the War on Terror has crossed the billion-dollar threshold: $1.13 billion per American service member killed.

This reflects two simultaneous trends: warfare has become astronomically more expensive (precision weapons, satellites, drones, logistics chains spanning the globe), and American casualties have plummeted thanks to body armor, armored vehicles, medevac helicopters, and field surgery that can save soldiers who would have died in any previous war. In WWII, roughly 30% of battlefield wounds were fatal. In Afghanistan, that figure dropped to about 10%.

Raw numbers lose their meaning after a while. Here's what America's war spending actually looks like when compared to things people can relate to:

The headline cost of a war is never the full cost. Veterans' care, disability payments, and mental health treatment continue for decades after the last shot is fired. The peak year for WWI veterans' care spending was 1969 - 51 years after the war ended. The peak year for WWII veterans' spending was 1986 - 41 years after V-J Day. The U.S. was still paying Civil War pensions into the 2020s, with the last known beneficiary (the daughter of a Union veteran) passing away in 2020.

For the War on Terror, Brown University estimates that veterans' care obligations through 2050 will total $2.2 to $2.5 trillion - and that figure will continue climbing. This is the single largest component of the War on Terror's total cost, exceeding even the direct military spending. And post-9/11 veteran suicide has claimed an estimated 30,000 lives - four times the number killed in combat.