 Designated in the middle of the 1920s, SR 181 primarily serves as a short route connecting traffic between Crestline and Ontario.For most of its lifespan, SR 181 had its western terminus at the signalized intersection where U.S. Route 30 (US 30) had crossed the Crawford–Richland county line.When the U.S. route was transferred onto a new freeway alignment in 2006, SR 181 was extended west along the former routing of US 30 to a new western terminus where it meets SR 61.