U.S. Highway 87 (US 87) is a north–south United States highway (though it is signed east–west in New Mexico) that runs for 1,998 miles (3,215 km) from northern Montana to southern Texas, making it the longest north-south road to not have a "1" in its number and the third longest north-south road in the country, behind U.S. 41 and U.S. 1. Most of the portion from Billings, Montana to Raton, New Mexico is co-signed along Interstates 90 and 25. It is also co-signed along the majority of Interstate 27 in Texas. As of 2004, the highway's northern terminus is in Havre, Montana, at U.S. Highway 2. Its southern terminus is in Port Lavaca, Texas. Route description Texas In Texas, US 87 is a north–south highway that begins near the Gulf Coast in Port Lavaca, Texas and heads north through San Antonio, Lubbock, Amarillo, and Dalhart to the New Mexico border near Texline. New Mexico US 87 continues in a northwesterly direction in New Mexico, and is signed by NMDOT primarily as an east–west route. It merges with US 64 (and thus the Santa Fe Trail National Scenic Byway) in Clayton, shortly after entering New Mexico. It continues to the northwest until Des Moines, when it takes a more westerly approach to Raton. In Raton, it separates from US 64 and merges with Interstate 25 and US-85, with which it remains concurrent through Raton Pass and into Colorado, though it is unsigned on much of the concurrency. Colorado US 87 remains concurrent with Interstate 25 throughout the state of Colorado, which is a rare occurrence for a US highway to have a concurrency with an Interstate in its entirety within state boundaries. Wyoming US 87 remains concurrent with Interstate 25 northward until exit 160 east of Glenrock where it joins US Route 20/US Route 26 from Glenrock to Casper. In Casper it splits from US-20/26 and rejoins I-25 at exit 186. It then remains concurrent with Interstate 25 northward until its terminus with Interstate 90. It then follows I-90 west to exit 44 where it runs up to Sheridan. A portion of US-87 has been washed out for several years along this stretch and "temporary" detour signs are posted directing US-87 traffic along Wyoming Highway 193 through Story. In Sheridan US-87 rejoins Interstate 90 into Montana. Montana US 87 remains concurrent with Interstate 90 westward until Billings, where it breaks off