A regulatory speed zone is the application, by Transportation Commission minute order, city ordinance, or county ordinance, of posted legal speed limits to sections of roadway where the numerical values of these special speed limits have been determined through engineering investigations of traffic and physical conditions.

Transportation Code, Chapter 545, Subchapter H, Section 545.362 established the method whereby the statewide maximum speed limit is altered by the national maximum speed limit laws. This function is administered by the Texas Department of Transportation (TxDOT) Traffic Operations Division (TRF) through the Texas Transportation Commission. However, Section 545.362 expired by its own terms upon repeal of the national maximum speed limit.