Route 187 is a short segment of highway running less than five miles (8 km) in Howard County, Missouri. Its easternn terminus is at Route 87 south of Glasgow; its western terminus is at Boone's Lick State Historic Site. No towns are on the route.

Route 187 begins at Boone's Lick State Historic Site in Howard County, where the road continues west as CR-328. The route heads northeast on a two-lane undivided road, passing through areas of fields and woods. Route 187 curves east and comes to its eastern terminus at Route 87 north of Boonesboro.

The entire route is in Howard County.