1949—Act Aug. 10, 1949, established Department of Defense as an Executive Department and reduced Departments of the Army, Navy, and Air Force to status of military departments in Department of Defense.

“United States Postal Service” substituted in text for “Post Office Department” pursuant to Pub. L. 91–375, §§ 4(a), 6 (o), Aug. 12, 1970, 84 Stat. 773, 783, which are set out as notes preceding section 101 of Title 39, Postal Service, and under section 201 of Title 39, respectively, which abolished Post Office Department, transferred its functions to United States Postal Service, and provided that references in other laws to Post Office Department be considered a reference to United States Postal Service.