U.S. Route 287 is a north–south United States highway. It is 1,791 miles (2,882 km) long. It serves as the major truck route between Fort Worth, Texas and Amarillo, Texas, and between Fort Collins, Colorado and Laramie, Wyoming. The highway is broken into two segments by Yellowstone National Park, where an unnumbered park road serves as a connector.

The highway's northern terminus is in Choteau, Montana, 100 miles (161 km) south of the Canadian border, at an intersection with U.S. Route 89. Its southern terminus (as well as those of US 69 and US 96) is in Port Arthur, Texas at an intersection with State Highway 87, five miles (8 km) up the Sabine River from the Gulf of Mexico. It intersects its parent route U.S. Route 87 twice, overlapping it from Amarillo, Texas to Dumas, Texas, and then crossing it in Denver, Colorado.

US 287 is the shortest route between Denver and Dallas-Fort Worth.

In Oklahoma, U.S. 287 remains within Cimarron County, the county at the end of the Panhandle. After crossing the state line north of Kerrick, Texas, the highway intersects State Highway 171 at its southern terminus. U.S. 287 continues northwest, crossing the Beaver River, toward Boise City, the county seat. On the east side of town, the highway becomes concurrent with U.S. 56, U.S. 64, U.S. 412, and Oklahoma State Highway 3. These five highways then enter the traffic circle in downtown Boise City. U.S. 287 emerges from the north side of the circle, as well as U.S. 385 and OK 3. These three highways head north to the Colorado state line. OK 3 ends there, while U.S. 287 and U.S. 385 continue onward into Colorado.

From Oklahoma, U.S. 287 and U.S. 385 enter into a very rural part of Colorado. They continue in a north/northwest direction through the state. The two Highways pass through the town of Campo, and make an interchange with U.S. 160 on the outskirts of Springfield. In Lamar and Carlton, the highways make an interchange with U.S. 50. Here U.S. 385 heads east on U.S. 50, and U.S. 287-U.S. 50 continue to the North. Just outside the town the highways make a sharp turn toward the west, and the road heading north is C-196. South of Wiley, U.S. 50 heads west, while U.S. 287 turns north toward Wiley. East of Eads, Colorado U.S. 287 turns toward the west again, briefly merging with C-96. In Eads C-96 continues toward the West, while U.S. 287 turns toward the North. Near Kit Carson, U.S. 287 again turns toward the west and merges with U.S. 40. Near Limon, the two highways make 2 interchanges with I-70 before passing through Limon. Then the two highways merge with I-70. Near the outskirts of Denver U.S. 36 merges with the group of highways making the road, I-70,U.S. 287,U.S. 36,U.S. 40.

Just past E-470, I-70 and U.S. 36 split to follow a more northerly course, while U.S. 287 and U.S. 40 continue west into Downtown Denver on Colfax Avenue. The I-25, U.S. 6, U.S. 87, and U.S. 85 interchange marks U.S. 287's second junction with its parent route, U.S. 87; the other is in Texas. Shortly thereafter, at a cloverleaf interchange with Federal Blvd, C-88 runs South, U.S. 40 continues west on Colfax, and U.S. 287 turns toward the north on Federal Blvd. After crossing U.S. 36 Denver-Boulder Turnpike, U.S. 287 turns west onto 120th Avenue where it overlaps C-128. Just before meeting U.S. 36 again in Broomfield, U.S. 287 bends back to the north, leaving C-128 which continues west through an interchange with C-121 and U.S. 36. At Baseline Road in Lafayette, C-7 joins U.S. 287 for about a mile, before C-7 splits to the west on Arapahoe Avenue towards Boulder. It intersects C-119 as it enters Longmont on the very busy Main Street, and then it intersects C-66 at the north edge of town. The road bypasses Berthoud en route to Loveland, where U.S. 287 splits into the pair of one-way streets Lincoln Avenue (northbound) and Cleveland Avenue (southbound) to pass through town. U.S. 287 passes through Fort Collins on College Avenue, merging with C-14 at Jefferson Street. On the edge of the mountains at Ted's Place C-14 splits and heads west into Poudre Canyon, while U.S. 287 continues north into Wyoming. The section of U.S. 287 between Fort Collins, Colorado and Laramie, Wyoming carries very heavy truck traffic and is regarded as quite dangerous.

U.S. 287 enters Wyoming through a pass between the Laramie Mountains to the east and the Medicine Bow Mountains to the west. In Laramie, U.S. 287 crosses I-80 and merges with U.S. 30 and the two highways continue to head North. After passing Medicine Bow, these highways turn west-southwest and return to I-80 near Walcott, where they merge with the interstate west until Rawlins. U.S. 287 branches off from I-80 and U.S. 30 and heads into the town. U.S. 287 merges with State Highways 76, 80, and 30 for a short distance just outside Rawlins, though WYO 36 ends when U.S. 287 branches to the northwest as a stand-alone highway. It is also possible to take the Business U.S. 287 (WYO 80, WYO 30) into Rawlins. In Downtown Rawlins, WYO 80 and 30 head toward the west while Business U.S. 287 heads to the north, merging with WYO 789 where WYO 30 and 80 split off the highway. A short while later Business U.S. 287 and WYO 789 merge with regular U.S. 287 which made a detour around the city. U.S. 287 and WYO 789 stay merged all the way to Lander, Wyoming, where WYO 789 heads toward the northeast and U.S. 287 heads toward the northwest. U.S. 287 merges with U.S. 26 in the very mountainous terrain of West/Central Wyoming, and the two highways head west. The highways enter Grand Teton National Park and make a big interchange in the town of Moran. In Moran, U.S. 287 and U.S. 26 meet U.S. 191 and U.S. 89. U.S. 26 heads south merging with U.S. 191 and U.S. 89. U.S. 287 heads North merging with U.S. 191 and U.S. 89, ending at the South Entrance of Yellowstone National Park. An unnumbered park road connects the two sections of U.S. 287 through Yellowstone.

The north section of U.S. 287 begins at the West Entrance of Yellowstone National Park in West Yellowstone. U.S. 287 and U.S. 191 split north of the town. U.S. 287 heads toward the northwest, merging with MT 2 north of Sappington, and running northeast. At I-90, MT 2 ends and U.S. 287 continues to head north. In Townsend, U.S. 287 merges with U.S. 12 and the two highways continue north. At I-15 (near Helena), U.S. 287 continues north on I-15 and U.S. 12 heads west through downtown Helena. Northeast of Wolf Creek, U.S. 287 and I-15 split with U.S. 287 heading northwest and I-15 heading northeast. U.S. 287 ends at U.S. 89 in Choteau.

When US 287 was first commissioned in 1939, it extended only from the south entrance of Yellowstone National Park to Denver, Colorado. The route was extended southward to the Gulf Coast at Port Arthur, Texas in 1940, and northward into Montana to US 89 at Choteau, Montana in 1965. U.S. 89 continues north of Choteau into Alberta as Provincial Highway 2 through the major cities of Calgary and Edmonton, connecting with a Canadian link to the Alaska Highway in the latter.

Included in the route of US 287 is former U.S. Route 370, which was commissioned in 1926 and connected Amarillo to Bowie, overlapping US 70 between Vernon and Wichita Falls.

The Canada to Gulf Highway Association, which later became the U.S. Highway 287 Association, was active from the 1910s until the 1970s to promote US 287 as a popular tourist route, and was composed of members from businesses and organizations in cities along the route.

The Wyoming state transportation department started widening U.S. Route 287 in 2009.