The original SH 84 was designated on August 21, 1923, as a route across West Texas from the New Mexico border through Brownfield and Post to Jayton, replacing portions of SH 18 and SH 39. On December 1, 1930, the section from Clairemont to Jayton was transferred to SH 70 when it was rerouted. In 1932, the route was co-located with US 380. In 1939, the co-designation with US 380 was completely removed.
