Highway 87 in the U.S. State of Montana is a route running northerly from the Idaho state line at Raynolds Pass to an intersection with U.S. Route 287 about 3 miles (4.8 km) west of Quake Lake, a distance of approximately 8.5 miles (13.7 km). The route traverses a high and arid mountain valley, flanked by the Horn Mountains; the land is mostly uninhabited. Raynolds Pass is on the Continental Divide.

The road across Raynolds Pass was first developed into a state highway in 1959, to provide a bypass route after an earthquake temporarily severed the roadway through the upper Madison River canyon to the east. Originally, the Raynolds Pass Road was designated as part of Montana Highway 287; the current number was assigned after US 287 was extended northward through Montana.

On October 9, 1922, a road located in the general location of MT 87 was added to the Montana State Highway system. By at least 1924, an auto trail known as the Banff Grand Canyon Road ran along the highway in the general location of MT 87. The next year, the highway had been given a graded dirt surface, and was designated as part of the Great White Way auto trail as well as the Banff Grand Canyon Road. Between 1925 and 1927, the auto trail designations were removed from the stretch of highway near present-day MT 87. By 1937, the main highway had been shifted north of the location of MT 87, and had been numbered as state highway 1. A road remained in the location of MT 87, although it was unnumbered. This road had also been extended several miles northward to Lyon.

By 1951, the highway had been reconstructed generally along MT 87's present location, and it had been upgraded to an improved gravel road. In 1959, the road in the location of MT 87 was rapidly improved in order to serve as an alternate routing to U.S. Route 287. Portions of US 287 around Hebgen Lake collapsed and crumbled as a result of the 1959 Yellowstone earthquake. After US 287 was fixed, the highway's importance decreased. In 1962, the portions of the highway from the southern terminus to present-day milepost 8.395 was reconstructed along the current location. In 1967, the rest of the highway was reconstructed along the present location. By 1987, the highway had been numbered as MT 87. The route had also been paved.