The Most Expensive Wars the United States Has Been Involved In

Since its inception in 1776, the United States of America has experienced wartime relations throughout almost its entire lifespan. Some of these wars were short, some were long, some were victories, and some were losses. Some of these wars cost the United States a whole lot of money. Here are the ten most expensive wars the United States have been involved in. The numbers provided have been adjusted for inflation.

10. Mexican-American War

"Battle of Churubusco--Fought near the city of Mexico 20th of August 1847 / J. Cameron."
Artists rendering of a battle during the Mexican-American war.

Coming in at number 10, the Mexican-American War cost American taxpayers around $2.4 billion to fight. The war was fought 1846-1848. It was the result of the annexation of Texas, in which the country of Texas became a state within the United States. Texas had originally been a territory of Mexico, but a revolution in 1836 led to the territory becoming its own country. The United States had not yet allowed Texas to become a state, following the revolution, fearing it could mess with the equality of states that were for/against slavery. This changed through the 1840s and led to the start of the war.

9. Revolutionary War

Painting of American soldiers during the Battle of Long Island. Wikipedia / Public Domain
Painting of American soldiers during the Battle of Long Island.

Though many people may believe the American Revolution began with the signing of the Declaration of Independence on July 4th, 1776, the war actually began in April of 1775. It all started when local militia in Massachusetts had a confrontation with British troops. The ensuing result was the American Revolution.

Just 13 months later, the United States would sign the Declaration of Independence declaring their freedom from the British. The war waged on, 1775-1783, with over 50,000-70,000 casualties on the United States side alone. The United States didn’t fight the war alone, having the aid of Spain, France, and the Netherlands in the battle. The overall cost of the war to the United States? About the same as the Mexican-American War – $2.4 billion.

8. Spanish-American War

Fought in 1898 and lasting just shy of 4 months, the Spanish-American War was fought between Spain and the United States. Originally, the Spanish were at war with Cuba, who had declared independence from them in 1895.

The United States had been getting pressure to get involved in the war to help Cuba, and that pressure came to a boiling point when then USS Maine randomly exploded in a harbor outside of Havana, Cuba and so the United States decided to declare war on Spain.

The USS Maine seen after sinking in Havanna, Cuba. Wikipedia / Public Domain
The USS Maine seen after sinking in Havana, Cuba.

But the war wasn’t just limited to the Caribbean. There was also a Pacific theater involving the Philippines and Guam. When the United States declared war, they did so in all regards. Thus, following their victory they acquired Puerto Rico, the Philippines, and Guam. The war cost the United States a grand total of $9 billion.

7. Civil War

President Abraham Lincoln was elected in to office in 1861, and was assassinated a year before the Civil War came to an end. Wikipedia / Public Domain
President Abraham Lincoln.

Slavery was one of the leading causes of the American Civil War. On one side, there was the Union North, which was against slavery and had elected President Abraham Lincoln into the country’s top position.

Lincoln ran on a platform of ending slavery, which led to the Confederate South seceding from the United States, creating the Confederate States of America, a group of slave states who shared the common interest of maintaining slavery. Because of this, the United States went to war against the Confederate States of America in 1861.

The war lasted until 1865 and cost the United States and the Confederate Sates each over $80 billion. It also resulted in the death of over 750,000 troops.

6. Gulf War

The Persian Gulf War saw short combat, but a large price tag. The war began in August of 1990 with Operation Desert Shield. This operation saw almost no actual combat and was the build up of the war. The U.S. alongside coalition countries brought in troops and supplies to the region for combat.

The combat portion of the Gulf War didn’t begin until January of 1991; this is referred to as Operation Desert Storm. In total, over 34 countries joined in on the war which was started due to Iraq invading Kuwait and annexing the country. The combat lasted just 42 days, ending in February of 1991. The Gulf War cost the United States $102 billion.

5. World War 1

American soldiers seen in combat during World War 1. Wikipedia / Public Domain
American soldiers seen in combat during World War 1.

The first World War is the fifth most expensive war for the United States. While the war began in Germany in 1914, the United States didn’t get involved until 1917.

The war would end just 18 months later, but the United States had already spent plenty of money on the war at the cost of $334 billion, which was about 14 percent of the Gross Domestic Product for the United States at the time.

4. Korean War

U.S. troops seen in Korea during the Korean War. Wikipedia / Public Domain
U.S. troops seen in Korea following World War II.

Fought on the Korean peninsula, the Korean war pitted Soviet Union-backed North Korea against United States-backed South Korea. North Korea invaded South Korea in 1950 in an attempt to make the land one country again.

Korea had been split following World War II when Japan (who claimed Korea) gave up the northern part to the Soviet Union. The United States moved into the South around the same time, and this led to a stalemate until 1950. The war never technically ended; rather, it ended in an armistice agreement and the two countries have technically been at war since. The United States spent a total of $341 billion on the Korean War.

3. Vietnam War

The Vietnam War is the third most expensive war the United States has ever fought in. War began when the communist North invaded the South. Much like the Korean War, the North was supported by the Soviet Union and China, while the South was supported by the United States.

This time, things were different, as the United States was unable to help South Vietnam achieve victory, and the country fell to the North with the fall of Saigon in 1975. The price tag for the United States? $738 billion.

2. War on Terror

Costing at least $1.6 trillion (2010 estimate), the War on Terror began following the 9/11 attacks on the United States. The war has changed over the years on who the United States was fighting as well as where the fight was raging.

It began in the fall of 2001, with the United States searching for Osama Bin Laden, then later moved to Iraq where U.S. troops overthrew Saddam Hussein and the focus has shifted from there. The war has yet to end.  The United States did pull troops out of the area during Operation New Dawn in 2010, but troops have since been placed back in the region.

1. World War II

U.S. troops preparing to land on Omaha Beach. June of 1944. Wikipedia / Public Domain
U.S. troops preparing to land on Omaha Beach. June of 1944.

The most expensive war the United States has fought in is World War II. The country suffered not only a huge loss of cash, but also a huge loss of troops. Over $4 trillion was spent on the second World War and over 400,000 U.S. troops died. United States involvement began in the war following the Japanese attack on Pearl Harbor and lasted until the end of the war in 1945.

Lincoln Riddle

Lincoln Riddle is one of the authors writing for WAR HISTORY ONLINE