It crosses the North Fork of the Red River near Sayre and runs through southern Elk City.

I-40 runs through the southside of El Reno as it enters the Oklahoma City metropolitan area.

This provides access to Tinker Air Force Base in east Oklahoma City.

The eastbound detour added 40 miles (64 km) and two hours to the typical trip.

Local firefighters directed traffic there 24 hours a day, with daytime temperatures approaching 100 °F (38 °C).

This is known to be the largest tornado ever recorded at 2.6 miles (4.2 km) wide and was responsible for eight fatalities and 151 injuries.

[6] This tornado crossed over I-40 at around 6:33 pm CDT after hitting peak strength and maximum width and did a 270-degree counterclockwise loop north of the Interstate, clipping SH-66 before traveling on and along the Interstate, approaching Oklahoma City at a very slow speed.

[7] On December 17, 2015, a Pasadena, Texas, man allegedly shot and killed two people on I-40 near Weatherford, Oklahoma.

[8] The original I-40 Oklahoma City Crosstown Expressway was built in 1966 mostly as an elevated route;[citation needed] however, this former stretch was too narrow for existing traffic and was frequently in disrepair.

[citation needed] A landscaped boulevard (Oklahoma City Boulevard) was completed in 2019, replacing the original I-40 Crosstown Bridge right-of-way through downtown Oklahoma City, similar to the I-30 reconstruction through downtown Fort Worth, Texas.