The United States' power in World War I was significant, both militarily and economically. The U.S. entered the war in 1917, and its involvement proved crucial to the Allied victory. The U.S. military's contribution was substantial, with over 4 million American soldiers serving overseas. Economically, the U.S. was the world's leading industrial power, providing the Allies with essential supplies and financial support.

The U.S. military's strength was evident in its rapid mobilization and deployment. By the end of the war, the American Expeditionary Force (AEF) numbered over 2 million men, making it the largest Expeditionary Force in the war. The AEF played a pivotal role in the final Allied offensive, the Hundred Days Offensive, which began in August 1918 and led to the German surrender in November 1918.

Economically, the U.S. was the world's leading industrial power, with a GDP of approximately $94 billion in 1918. The U.S. provided the Allies with over $10 billion in financial support and supplied them with vast quantities of war materials, including 350,000 tons of food, 3 million tons of coal, and 1.5 million tons of steel. The U.S. also produced over 2 million machine guns, 300,000 artillery pieces, and 500,000 aircraft.

The U.S. entry into the war also had a significant psychological impact. The American public's support for the war effort was strong, and the U.S. government's propaganda campaigns were effective in mobilizing the population. The U.S. also played a key role in shaping the peace negotiations that followed the war, particularly through the efforts of President Woodrow Wilson and his Fourteen Points.

In summary, the United States' power in World War I was substantial, with its military and economic contributions being pivotal to the Allied victory. The U.S. military's rapid mobilization and deployment, combined with its industrial might and financial support, played a crucial role in the war's outcome.