Interstate 40 (I-40) is an Interstate Highway in Oklahoma that runs 331 miles (533 km) across the state from Texas to Arkansas. West of Oklahoma City, it parallels and replaces old U.S. Highway 66 (US-66), and, east of Oklahoma City, it parallels US-62, US-266, and US-64. I-40 is the longest Interstate highway in Oklahoma.

Quick Facts Route information, Length ...

Interstate 40
I-40 highlighted in red
Route information
Maintained by ODOT
Length	331 mi (533 km)
Existed	1957[1]–present
NHS	Entire route
Major junctions
West end	I-40 at the Texas state line
Major intersections	US 283 in Sayre US 81 in El Reno I-344 / Kilpatrick Turnpike in Oklahoma City I-44 in Oklahoma City I-35 in Oklahoma City I-235 / US 77 in Oklahoma City I-240 in Oklahoma City Indian Nation Turnpike in Henryetta US 69 in Checotah Muskogee Turnpike near Webbers Falls
East end	I-40 at the Arkansas state line
Location
Country	United States
State	Oklahoma
Counties	Beckham, Washita, Custer, Caddo, Canadian, Oklahoma, Pottawatomie, Seminole, Okfuskee, Okmulgee, McIntosh, Muskogee, Sequoyah
Highway system
Interstate Highway System Main Auxiliary Suffixed Business Future Oklahoma State Highway System Interstate US State Turnpikes
← SH-39 → SH-42

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Cities along the route include Erick, Sayre, Elk City, Clinton, Weatherford, Oklahoma City and its suburbs (El Reno, Yukon, Del City, and Midwest City), Shawnee, Okemah, Henryetta, Checotah, and Sallisaw.

I-40 enters Oklahoma near Texola in Beckham County. It crosses the North Fork of the Red River near Sayre and runs through southern Elk City. It then cuts across northwest Washita County before entering Custer County. There, it passes through Clinton and Weatherford. After leaving Weatherford, I-40 then runs across northern Caddo County. After that, it enters the Oklahoma City metropolitan area at Canadian County.

I-40 runs through the southside of El Reno as it enters the Oklahoma City metropolitan area. It then passes through Yukon before entering Oklahoma City city limits. In west Oklahoma City, I-40 has a junction with I-44. It then runs just south of downtown Oklahoma City on a new 10-lane section.^[2] I-40 then interlines with I-35 at the Dallas Junction complex. This forms a concurrency with it for two miles (3.2 km). After the Dallas Junction, I-40 then passes through Del City and Midwest City on the Tinker Diagonal. This provides access to Tinker Air Force Base in east Oklahoma City.

In far eastern Oklahoma City, I-40 meets I-240 in a partial junction. Afterward, it passes through the northside of Shawnee. This marks the eastern end of the Oklahoma City metropolitan area. In Henryetta, I-40 serves as the northern terminus of the Indian Nation Turnpike. In McIntosh County, it crosses the northernmost arm of Lake Eufaula. Afterward, it meets US-69 south of Checotah.

Near Webbers Falls, I-40 is the southern terminus of the Muskogee Turnpike. It then crosses the Arkansas River before passing through southern Sallisaw. The Interstate crosses into Arkansas north of Moffett.

This section needs expansion. You can help by adding to it. (May 2008)

West of Oklahoma City, I-40 parallels and replaces Old US-66. US-66 was decommissioned in Oklahoma in 1985.

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. In response, the I-40 Crosstown Expressway has been relocated a few blocks south of the original route and the original bridge torn down. The project was completed in February 2012.^[2]

The new I-40 Crosstown Expressway has been designed to carry more than 170,000 vehicles per day traveling at 60 mph (97 km/h) using at least 10 lanes for traffic and has breakdown lanes for disabled vehicles and future lane expansion.

When the new crosstown opened in 2012, nearly 95% of non–rush hour traffic was considered 'through traffic' (i.e., not transferring to or from downtown streets).^{[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.

I-40 has eight business routes in Oklahoma, six of which are old alignments of US-66. A number of other old alignments of US-66 are also present west of Oklahoma City.

• Interstate 40 Business (I-40 Bus., formerly US-66) in Erick is a business loop that runs from I-40 two miles (3.2 km) west of Erick to the old alignment of US-66, through Erick, and back to I-40 four miles (6.4 km) east of Erick.
• I-40 Bus. (formerly US-66) in Sayre is a business loop that begins two miles (3.2 km) south of Sayre at US-283, runs north into the city, and then leaves Sayre to the east, rejoining I-40 two miles (3.2 km) east of US-283.
• I-40 Bus. (formerly US-66) in Elk City is a business loop that begins at exit 32 seven miles (11 km) west of Elk City. It runs for 10 miles (16 km) through Elk City, rejoining I-40 at exit 41.
• I-40 Bus. (formerly US-66) in Clinton is a business loop that begins at exit 65, runs five miles (8.0 km) through Clinton, and rejoins I-40 at exit 69.
• I-40 Bus. (formerly US-66) in Weatherford is a business loop that exits I-40 at exit 82B, runs four miles (6.4 km) through Weatherford, and rejoins I-40 at exit 82.
• I-40 Bus. (formerly US-66) in El Reno is a business loop that exits I-40 at exit 119, runs eight miles (13 km) through El Reno, and rejoins I-40 at exit 125, the interchange with US-81.
• I-40 Bus. (formerly US-62/US-75) in Henryetta is a business loop that leaves I-40 at exit 237, runs four miles (6.4 km) through Henryetta, and rejoins I-40 at exit 240, the interchange with US-75 and the Indian Nation Turnpike.
• I-40 Bus. in Sallisaw is a business loop that leaves I-40 at exit 308 (US-59) runs four miles (6.4 km) through Sallisaw, and rejoins I-40 at exit 311, US-64.

I-40 has one auxiliary route in Oklahoma:

• I-240: A bypass of the southside of Oklahoma City

• U.S. Route 66 in Oklahoma