Why did the United States become involved in World War I?

Germany attempted to instigate a conflict between the United States and Canada to draw American attention away from Europe.

It came in part from the unrestricted submarine warfare Germany waged on all nations that traded with its enemies.

The United States entered the war as a requirement of the American-French alliance from the Revolutionary War.

An attempted assassination of President Wilson by a German-born American convinced the United States to enter the war.

The primary reason the United States became involved in World War I was due to the unrestricted submarine warfare conducted by Germany. This led to the sinking of American ships and the loss of American lives, prompting President Woodrow Wilson to declare war on Germany in April 1917. Additionally, the desire to protect American economic interests and support the Allied powers against the Central Powers also played a role in the decision to enter the war.