This is a list of formations in the United States Army during World War I. Many of these formations still exist today, though many by different designations.
The role of depot brigades was to receive and organize recruits, provide them with uniforms, equipment and initial military training, and then send them to France to fight on the front lines. The depot brigades also received soldiers returning home at the end of the war and completed their out processing and discharges. Depot brigades were often organized, reorganized, and inactivated as requirements to receive and train troops rose and fell, and later ebbed and flowed during post-war demobilization.
Depot brigades were organized into numbered battalions (1st Battalion, 2d Battalion, etc.), which in turn were organized into numbered companies.
The major U.S. depot brigades organized for World War I, which remained active until after post-war demobilization included: