See also: Formations of the United States Army.
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.
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.
See also: List of United States Army divisions during World War II.