This is a list of formations of the United States Army during the World War II. Many of these formations still exist today, though many by different designations. Included are formations that were placed on rolls, but never organized, as well as "phantom" formations used in the Allied Operation Quicksilver deception of 1944—these are marked accordingly.
In addition, the presence of three additional "corps" were advertised to German and Japanese espionage efforts: the XXXIII, XXXV Airborne, and XXXVII Corps. The presence of these non-existent headquarters were portrayed by radio deception, and other efforts like creating unit patches. See United States Army deception formations of World War II.
Airborne, armored, cavalry, infantry, and mountain divisions are grouped separately. The numbering system for the airborne and mountain divisions are a continuation of the infantry numbering system—"phantom" formations are an exception to that numbering system.