1939 general re-description of highway system (Texas)

In 1939, the Texas Highway Department renumbered all highways that ran concurrently with U.S. Highways. Sections of state highways that were separated by a concurrency with a US Highway were renumbered, and all suffixed routes (that did not become part of other highways or other state highways) were renumbered.

Source: Wikipedia — 1939 general re-description of highway system (Texas) (CC BY-SA 4.0)