On July 15, 1935, the section west of Wimberley was cancelled. On September 22, 1936, SH 80 was extended to Karnes City, replacing a portion of SH 112. On September 26, 1939, SH 80 was extended southwest to the Atascosa–Karnes county line, replacing SH 312.
On October 12, 1925, SH 80 was extended to Wimberley, but this did not take effect until January 1, 1926. On April 6, 1932, SH 80 had a planned extension south to Nixon designated. On February 13, 1934, SH 80 was extended west to south of Blanco.