Highway 200 in the U.S. State of Montana is a route running westerly covering the entire state of Montana, from the starting point of ND 200 near Fairview, Montana to ID 200, near Heron, Montana. It is part of a chain of state highways numbered 200 which extends through Idaho, Montana, North Dakota, and Minnesota.

Highway 200 helps to connect many small towns located in central Montana and the vast plains area of eastern Montana, to larger western Montana cities such as Great Falls and Missoula. It is also the longest route signed as a state highway in the United States.

The highway runs parallel to the Blackfoot River from McNamara to Milltown. The highway is subject to hazardous driving conditions in the winter, particularly due to black ice. This road crosses Rogers Pass on the continental divide.