In the US state of Texas, Interstate 40 (I-40) runs west–east through the panhandle in the northwest part of the state. The only large city it passes through is Amarillo, where it meets the north end of I-27. History Before the U.S. Highway system, this system of interconnected highway from New Mexico to Oklahoma was part of the Texas highway system and a portion of the Ozark Trails which closely paralleled the Chicago, Rock Island and Pacific Railway. When the United States Numbered Highway system was introduced in 1926, U.S. Highway 66 (US 66) across the Texas Panhandle was designated along existing roads in the Texas highway network. The entire route was paved by 1938. There have been various realignments, including one in 1959, to allow expansion of the Amarillo Air Force Base. In 1956, the Interstate Highway Act designated US 66 through Texas as a section of highway eligible for limited access upgrades. During the next 20 years, most of the highway was upgraded in place to keep construction costs low. With the limited access of the Interstates, towns on the highway had to be bypassed. Most towns requested to remain as close to the new highway as possible to minimize tourism losses. Bypassed towns included Glenrio, Adrian, Vega, Conway, Groom, Jericho, Alanreed, McLean, and Shamrock. A new routing along the south end of downtown Amarillo was also built, connecting with the already-built expressway leading south from downtown toward Canyon. In 1985, the entire designation of US 66 was removed as the entire route had been displaced by I-40. Route description I-40 in Texas is one of a few Interstate Highways with at-grade intersections. The westernmost part of I-40 in Texas, near the New Mexico border, lacks the frontage roads typical to Texas freeways, and eight driveways for ranches directly intersect the main lanes of I-40, in violation of Interstate standards. The entirety of I-40 in Texas is located in the panhandle. I-40 enters Texas from New Mexico just north of Glenrio. The highway's first exit, exit 0, is for Business Interstate 40-A (Bus. I-40-A), which serves the town of Glenrio. I-40 briefly runs through Deaf Smith County before entering Oldham County. The Interstate gains frontage roads between exits 15 and 18 and turns from a northeast direction into a straight east direction. I-40 bypasses the town of Adrian before turning southeast. I-40 next bypasses the town of Vega,