| State: | OK |
| Type: | SH |
| Route: | 6 |
| Maint: | ODOT |
| Map Custom: | yes |
| Map Notes: | OK 6 mainline in red |
| Length Mi: | 121.8 |
| Direction A: | South |
| Direction B: | North |
| Terminus A: | at the Texas state line |
| Junction: | |
| Terminus B: | near Sweetwater |
| Previous Type: | SH |
| Previous Route: | 5 |
| Next Type: | SH |
| Next Route: | 7 |
State Highway 6, abbreviated SH-6 or OK-6, is a state highway in Oklahoma. It runs in a 121.8miles crescent through the southwestern part of the state, running from the Texas state line north of Quanah, Texas, to SH-152 in the unincorporated town of Sweetwater. There are no letter-suffixed spur branching from SH-6.
SH-6 was added to the state highway system in 1954. The highway was later extended from its original extent; westward from Elk City in 1957 and southward to Texas in 1975.
After crossing the Red River, State Highway 6 leaves Texas, becomes SH-6 and continues headed northeast, passing through the small Jackson County towns of Eldorado and Olustee. Highway 6 meets US-62 five miles (8 km) west of Altus.[1] SH-6 makes a right turn at this point to overlap US-62 into Altus.
In Altus, SH-6 takes a turn to the north to overlap US-283. North of Blair, US-283 heads due north while SH-6 turns toward the northwest. SH-6 crosses US-283 once more before the state highway continues to the north toward Granite, where it meets SH-9.
North of Granite, SH-6 runs along the Beckham–Washita county line until sharing a 4-mile (6.4 km) concurrency with SH-55, moving into Beckham County.[1] After splitting away from SH-55, it meets SH-152 for the first time (it will meet SH-152 at its northern end.)
SH-6 continues north to have an interchange with Interstate 40 in Elk City. It overlaps Business Loop I-40 for four miles (6.4 km) on the north side of the city.[1] At this point the north - south highway curves to the west. It crosses US-283 (again), and then ends at SH-152 in Sweetwater.
The original State Highway 6 extended from the Texas state line near Colbert to the Kansas state line north of Vinita.[2] When the United States Numbered Highways system was established in 1926, the vast majority of the highway was overlapped by US-75 and US-73.[3] (Later, this corridor would form the majority of US-69 in Oklahoma). As a result, the original SH-6 designation was decommissioned soon after the establishment of the U.S. highway system.
The SH-6 designation remained unused until August 21, 1954, when it was assigned to a highway beginning at US-283 east of Mangum, extending north through Granite and Retrop, and ending at US-66 in Elk City.[4] The highway was extended west along SH-73 to its current northern terminus on January 21, 1957.
SH-6 was extended to the south on July 7, 1975, bringing it to Altus by way of a concurrency with US-283, where it joined US-62 in another concurrency, headed west. West of Altus, the route split off and headed southwest to the Texas state line. In addition to the U.S. routes, SH-6 was concurrent with SH-44 between that route's current southern terminus and Eldorado, where it ended; thereafter, SH-6 followed SH-34 to the Red River. To remove the redundant designations, both SH-34 and SH-44 were truncated to their current southern terminus on January 5, 1987.
SH-6 was realigned twice in 2004 to allow SH-6 a straighter route in situations where it was concurrent with another highway. The first such section removed a portion of the US-283 concurrency between Blair and Granite; the second realignment took place on the SH-55 concurrency north of Retrop. Both of these changes were applied to the highway on February 2, 2004. No further changes to the highway's route have taken place since then.