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.

It overlaps Business Loop I-40 for four miles (6.4 km) on the north side of the city.

[citation needed] 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.

West of Altus, the route split off and headed southwest to the Texas state line.

To remove the redundant designations, both SH-34 and SH-44 were truncated to their current southern terminus on January 5, 1987.