It begins at the Texas state line, serving as a continuation of Texas State Highway 152, and continues east to end at I-344 (John Kilpatrick Turnpike) in southwest Oklahoma City, a length of 145 miles (233 km).

Along its route it serves three county seats: Sayre, Cordell, and Oklahoma City (which is also the state capital).

SH-41 was extended east to Oklahoma City around 1934 and west to the Texas state line around 1938.

SH-152 begins at the Texas state line in Roger Mills County.

(Located at this intersection is an abandoned Apco station, which was used in a scene from the movie "Rain Man").

Upon crossing into Oklahoma County, SH-152 becomes a four-lane undivided expressway, before heading northeast.

[7] On March 5, 1979, the eastern terminus was pushed back a half-mile west, to the intersection of Interstate 44 and S.W.

[6] On February 2, 2004, SH-152 was removed from Newcastle Boulevard and placed on the newly extended Airport Road freeway.

Starting in the existing eastern terminus, I-240 will run concurrent with I-40 to the Kickapoo Turnpike, then turn north and follow the Kickapoo Turnpike north to I-44 (the Turner Turnpike), then turn west along I-44 to the Kilpatrick Turnpike, following that road west and south to its current southern terminus at SH-152, then turning east along SH-152 and following that road east to I-44, which it will overlap until reaching the current western terminus of I-240.

It heads west along Orient Avenue through town, until it reaches Rambo Street.

SH-42 was first added to the state highway system on July 20, 1939, at which time it had been graded, but not yet surfaced.