SH 55's southern terminus is at County Road 81 northeast of Fleming, and the northern terminus is at SH 138 in Crook.

SH 55 runs 5.7 miles (9.2 km), starting at a junction with U.S. Highway 138 in Crook, then south across the South Platte River to I-76.

The highway ends at CR 81 northeast of Fleming.

The entire route is in Logan County.

Media related to Colorado State Highway 55 at Wikimedia Commons