State Route 187 or SR-187 is a 22.995-mile (37.007 km) state highway that serves as a north-south connection through central Franklin and Marion Counties. SR-187 intersects US-43 at its southern terminus and SR-24 at its northern terminus.

State Route 187 begins just north of Hamilton at its intersection with US-43. From this point, the route travels in a northerly direction except for a brief turn to the east where it meets SR-172 in Hodges. From Hodges, SR-187 returns to its northerly routing in route to its northern terminus at SR-24 in Belgreen.