South Dakota Highway 377 (SD 377) is a 2-mile-long (3.2 km) state route that runs entirely within Jackson County, South Dakota. It begins at its intersection with SD 44 in Interior, and runs in a northeasterly direction to its northern terminus at its intersection with SD 240 in the Badlands National Park.

SD 377 begins at an intersection with SD 44 in northeastern Interior. It is a near-straight two-lane highway for its entire length. It enters Badlands National Park and ends at SD 240 near the park's headquarters.

The entire route is in Jackson County.