SH 70 begins in far northeasternCoke County at a junction withUS 277 north ofBronte.[2] The highway soon crosses intoNolan County, where it serves as the northern terminus ofSH 153.[4] The first large city along SH 70's route isSweetwater; here, the route is concurrent withInterstate 20 andUS 84 along the south side of the city, between I-20's Exits #244 and #247, before it resumes its northward course and entersFisher County.[5] SH 70 intersectsUS 180 inRoby andSH 92 inRotan.[6] Continuing north intoKent County, the route begins a concurrency withUS 380 that lasts untilJayton.[7] InDickens County, SH 70 serves as the northern terminus ofSH 208 and passes through the east and north side ofSpur before reachingDickens and an intersection withUS 82 /SH 114.[8][9] After heading almost due north from here, the route entersMotley County and passes through the town ofRoaring Springs.[10] The next major city along the route isMatador, where SH 70 andUS 70 intersect one another (along withUS 62).[11] After leaving Matador, SH 70 entersHall County, where it has a brief concurrency withSH 86 throughTurkey.[12] The highway then briefly turns to the northwest and entersBriscoe County, beginning a brief concurrency withSH 256, before turning to the west and reentering Hall County; the two routes separate near the community ofSouth Brice.[13] SH 70 resumes a more northerly path intoDonley County, and has a short concurrency withUS 287 throughClarendon.[14] After the two routes separate, SH 70 heads due north to a junction withInterstate 40 at its Exit #124, near the Donley–Gray County line.[15] Northbound SH 70 is concurrent with the freeway for about 3.5 mi (5.6 km) before the routes split at I-40 Exit #121. SH 70 continues north intoPampa, where it intersectsUS 60 and has a half-mile duplex withSH 152. After leaving Pampa, the route turns more to the north-northeast, and enters the sparsely populatedRoberts County, where its only intersections are with a fewfarm to market roads that connect to the county seat ofMiami.[16][17] SH 70 then entersOchiltree County and reaches its northern terminus atUS 83 south ofPerryton.[3] While the current official route description of SH 70 indicates a concurrency with US 83 to a junction withSH 15 in Perryton, that roadway is presently signed only as US 83, which agrees withTxDOT's County Map Book, and signage in Perryton at the SH 15 junction with US 83 directs traffic to SH 70 using "TO SH 70" markers.[1][3]
SH 70 was originally designated on August 21, 1923, fromAspermont toSan Angelo along a portion of the originalSH 4, which had been shifted farther east.[18] On October 13, 1925, it was routed throughRobert Lee.[19] On September 18, 1929,SH 70 was rerouted to bypass Robert Lee. Part becameSH 70A, but Robert Lee to San Angelo was cancelled, but restored asSH 208 on July 16, 1934.[20] On December 1, 1930, the route had been rerouted north toJayton, replacingSH 161 and a small portion ofSH 84.[21] On September 26, 1939, SH 70 was extended north from Jayton toDickens, absorbing a portion ofSH 18. Significant extension came on October 10, 1947, when SH 70 was extended toPerryton in the northern Panhandle; this was due to the realignment ofUS 62 between Matador andRalls, bypassing Dickens, and the cancellation of SH 18 from Matador to Perryton.[22][23] On February 12, 1948,US 277 was rerouted to a more westerly alignment betweenAbilene, Texas andSan Angelo, Texas, and the section from just south of Blackwell to near San Angelo was transferred to that route.[1][24] On September 27, 1957, SH 70 was shifted to a more westerly alignment in Dickens, andLoop 120 was extended along the old route of SH 70 through the city.[25]
A spur,SH 70A, was designated on September 18, 1929, from Robert Lee east to Bronte.[20] This route was renumbered asSH 158 on March 19, 1930.
On September 27, 1985,Texas State Highway Loop 549 was designated as a bypass of SH 70 in Sweetwater and was signed, but not designated, as SH 70, and the old route was signed as a business route. On June 21, 1990, SH 70 was designated on Loop 549, and the old route of SH 70 became a business route, cancelling Loop 549.
SH 70 has one business route,Business SH 70-G inSweetwater, which is a former alignment of the state highway through that city. The route was designated in 1990, when SH 70 was rerouted along the south and east side of the city to use theI-20 freeway. The business route is also concurrent withBL I-20 through downtown Sweetwater.[26][27]
^The certified length given is shorter than the actual mileage, as the TxDOT description of SH 70 considers it to be discontinuous at rather than concurrent with all Interstates and US highways.
^The certified length given is shorter than the actual mileage, as the TxDOT description of Bus. SH 70 considers it to be discontinuous at rather than concurrent with BL I-20 in Sweeywater.