) is an Interstate Highway, entirely in the US state of Texas, running north from Lubbock to I-40 in Amarillo. These two cities are the only control cities on I-27; other cities and towns served by I-27 include (from south to north) New Deal, Abernathy, Hale Center, Plainview, Kress, Tulia, Happy, and Canyon. In Amarillo, I-27 is commonly known as the Canyon Expressway (or Canyon E-Way), although it is also called Canyon Drive on its access roads. I-27 was officially designated the Marshall Formby Memorial Highway after former attorney and State Senator Marshall Formby in 2005.
The Interstate officially begins north of County Road 7500, at the beginning of access control on the four-lane US 87 freeway, at the very southern edge of Lubbock's city limits. Mile 0 is currently posted near 77th Street, about five blocks south of Loop 289. Exit numbering begins just to the south, with exit 1 at the 82nd Street interchange; the freeway becomes six lanes at its north end. With the extension being approved on September 3, 2024, by the Federal Highway Administration (FHWA) and the Texas Transportation Commission on September 26, 2024, In 1926, it became part of US 385, which was absorbed into US 87 in 1935. The SH 9 overlap was dropped in the 1939 renumbering. Paving began in 1929 near Plainview and was almost complete by 1940, The Canyon Expressway, a freeway upgrade of US 87 (also US 60 there) between Canyon and Amarillo, was built in the late 1950s and early 1960s. This highway, with a design speed of , included frontage roads along its entire length and ended in each city with a Y interchange: short sections of freeway were built through New Deal, Abernathy, and Hale Center, and interchanges were built at US 70 and SH 194 on the new bypass of Plainview and at SH 86 (toward the west) south of Tulia. The original two-lane road, where bypassed, became Loop 461 (in New Deal in 1968; marked as Bus. US 87-G), Loop 369 (in Abernathy in 1962), a local street (in Hale Center), and Loop 445 (in Plainview in 1967; marked as Bus. US 87-G).
I-27 was not part of the original Interstate Highway System chosen in the 1950s; the spur from I-40 to Lubbock was authorized with the Federal-Aid Highway Act of 1968, which added to the system. George H. Mahon, member of the US House of Representatives from 1935 to 1979 and chair of the House Committee on Appropriations after 1964, helped secure funding for the road. Texas officially designated the highway in early 1969, originally running from US 62 near downtown Lubbock to I-40 in Amarillo; the definition was extended south through Lubbock to the south side of the loop in early 1976. Most of the Happy–Canyon bypass was built along the two-lane FM 1541, which now ends at exit 103 southeast of Canyon.
The final section of I-27 to be built was through Lubbock, inside Loop 289; this was built in the early 1990s and completed on September 3, 1992. On that day, a ceremony at the 34th Street overpass opened the road from 19th Street (US 62) to 54th Street, completing Texas's portion of the Interstate Highway System. At its south end, the new I-27 connected to an existing freeway upgrade of US 87, built about 1970, The old route of US 87 through Lubbock became Bus. US 87-G upon completion of I-27. Two business loops of I-27 have been designated: through Plainview (former Loop 445) in early 1991 and through Hale Center (formerly a local street) in 2002.
The completion of I-27, costing a total of $453.4 million (equivalent to $ in ), encouraged growth along the highway: toward the northside of Lubbock and the southwest in Amarillo. Many other areas of Lubbock, however, have not seen this growth. Plainview, the largest city between Lubbock and Amarillo, has the only significant retail cluster outside the two terminal cities and has attracted several industries.
On September 5, 2024, the Federal Highway Administration (FHWA) approved a southern extension of I-27 from its previous terminus at Loop 289 to north of County Road 7500, the new limit for access control on the US 87 freeway north of that point. instead recommending limited upgrades to the three corridors studied: SH 349 via Midland and Odessa to east of Fort Stockton, US 87 via Big Spring to Sonora or Junction, and US 84 via Sweetwater to Sonora or Junction. Of the three corridors, the Sweetwater route came the closest to warranting a freeway. The Transportation Equity Act for the 21st Century, passed in 1998, designated I-27 as part of the Ports to Plains Corridor, a High Priority Corridor from Mexico at Laredo to Denver. This corridor crosses I-20 at Big Spring and Midland (via a split) and I-10 at Sonora. The part of the Ports-to-Plains Corridor within Texas was a proposed Trans-Texas Corridor. Some parts of this plan have I-14 possibly ending where I-27 will cross I-20. The Texas Department of Transportation (TxDOT) recommends studying I-27 extension again. I-27 is planned to be extended from Loop 289 to FM 1585 (Loop 88).
On June 10, 2019, Governor Greg Abbott signed Texas House Bill 1079, which authorizes a comprehensive study to extend I-27 north of Amarillo and south of Lubbock to Laredo. The proposed route south of Lubbock would have the Interstate go to Lamesa, then split with one route going toward Midland and the other traveling to Big Spring. The two routes would then merge near Sterling City, travel through San Angelo and Del Rio, travel near the border until Eagle Pass, turn east to Carrizo Springs, then travel south to Laredo.
In March 2024, TxDOT released an implementation plan that listed all the projects that were planned for the I-27 project in the state.
In June 2024, it was announced that I-27 would potentially run along the Heartland Expressway and the Theodore Roosevelt Expressway through Nebraska, South Dakota, North Dakota, and Montana. It also forms part of the Great Plains International Trade Corridor, continuing north to Saskatoon, Saskatchewan. Currently, no Interstates connect to Saskatchewan.
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On March 15, 2022, the 2022 Consolidated Appropriations Act was signed by President Joe Biden that added the extension of I-27 north to Raton, New Mexico, and south to Laredo to the Interstate Highway System. A bill introduced in March 2023 would explicitly designate the extension as I-27 with two auxiliary routes numbered I-227 and I-327. I-227 is proposed to be routed via SH 158 from Sterling City to Midland and SH 349 from Midland to Lamesa; I-327 would utilize US 287 from Dumas to the Oklahoma state line.<!--Lubbock Avalanche-Journal erroneously states US 87 being used for the IH 327 corridor from Dumas to Oklahoma border; US 87 does not enter Oklahoma.--> It would also formally name the Interstate the Ports-to-Plains Corridor. The bill was introduced by legislators from both Texas and New Mexico. On August 1, 2023, the legislation passed through the U.S. Senate with some slight modifications; I-227 was redesignated as I-27W with I-27 between Sterling City and Lamesa redesignated as I-27E and I-327 was redesignated as I-27N. The act was passed again by the Senate in March 2024 after some changes were made in the U.S. House of Representatives in December 2023.