In 1926, US 83, US 96 and US 77 were overlaid on most of SH 12. On March 19, 1928, SH 12B became part of an extension of SH 2. On March 18, 1929, the section of SH 2 from Laredo to Pharr was changed back to SH 12B. On August 6, 1929, SH 12B became part of an extension of SH 4. On that same day, SH 12 was truncated to Pharr, with the portion south of there being transferred to SH 4. On November 16, 1929, SH 12 was to be built through Fannin Park. On March 19, 1930 SH 12 was rerouted to bypass the park, and the section from Fannin to Fannin Park was renumbered SH 162.