The title was enacted into positive law by Pub. L.Tooltip Public Law (United States)95–473, § 1, October 17, 1978, 92 Stat.1337; Pub. L.Tooltip Public Law (United States)97–449, § 1, January 12, 1983, 96 Stat.2413; and Pub. L.Tooltip Public Law (United States)103–272, July 5, 1994, 108 Stat.745 (subtitles II, III, and V-X)
During the time between when the Title 49 positive law codification began in 1978 and when it was completed in 1994, the remaining non-positive law sections were placed in an appendix to Title 49.[1][2]
In 2010, Congress enacted Title 51 as a new positive law title concerning NASA and commercial space programs. As part of the codification, the heading of Subtitle IX was marked "transferred" and the contents of such subtitle were moved to Title 51.[4] Five years later, the FAST Act inserted a new Subtitle IX. The heading of new Subtitle IX was given the heading "Multimodal Freight Transportation."[5]
^Fixing America's Surface Transportation Act, Pub. L.Tooltip Public Law (United States)114–94 (text)(PDF), Sec. 8001(a), 129 Stat.1312, 1604; Act of 2015-12-4.