SH 33 was originally proposed on November 19, 1917 from El Paso to the New Mexico border. On September 5, 1918, SH 33 extended southwest to the Mexico border. On March 19, 1919, another section of SH 33 was added from the New Mexico border through Amarillo northeast through Panhandle then east through Wheeler and into Oklahoma. This section was proposed as SH 13 until November 19, 1917, when SH 13 was rerouted off of this proposed road. On November 27, 1922, SH 33 was rerouted over SH 33A so that it went northeast from Pampa to the Oklahoma border near Higgins. The section from Pampa via Wheeler to the Oklahoma border was cancelled. In 1926, it was cosigned with US 366 southwest of Amarillo. By 1928, it was cosigned with US 164 northeast of Amarillo. By 1933, it was still under construction. Both US 366 and US 164 became part of an extended US 60. On November 24, 1936, SH 33 Loop was designated in Bovina. On September 26, 1939, SH 33 had been cancelled, as the entire northern section was part of US 60 and the southern section was part of US 54. SH 33 Loop was renumbered as Loop 47. SH 33 was reassigned on October 26, 1954, when SH 170 was renumbered as SH 33 to match Oklahoma. SH 33A was originally a spur route of SH 33, splitting off in Pampa, and travelling northeast next to the a rail route. It was designated as an intercounty highway on September 15, 1919, but was changed to a state highway, SH 33A, on January 17, 1921. On November 27, 1922, it had been renumbered as the main route. On February 17, 1925, it had been moved to a new route from Pampa via Wheeler to the Oklahoma border. On September 21, 1925, the section from Wheeler to Oklahoma was cancelled. On August 1, 1929, it had been moved to a new route from Miami to Mobeetie. On February 26, 1930, it was rerouted to go west to Pampa instead of Miami, and it extended east to Wheeler. On March 19, 1930, it was renumbered as SH 152. SH 33B was a proposed route from Clarendon north through Pampa, and continuing north into Oklahoma. It was designated as an intercounty highway on June 21, 1920,, but was changed to a state highway, SH 33B, on January 17, 1921. The route was cancelled on November 27, 1922. On February 19, 1923, it was restored, but only from Pampa to Oklahoma. On August 21, 1923, the route had been renumbered as SH 88.
