The 90th Infantry Regiment was a Regular Army infantry regiment of the United States Army, which existed during World War I and World War II. The regiment was organized in 1918 during World War I with the 20th Division, but the war ended before it could be deployed overseas; it was demobilized in spring 1919. During World War II, the 90th Infantry was again activated with the 10th Light Division (the future 10th Mountain) in mid-1943, but was transferred to become a nondivisional separate training unit in early 1944, inactivating in mid-1945.
