The route is lightly traveled; the busiest section of the road as measured by the Ohio Department of Transportation (ODOT) is within the SR 7 interchange in Bellaire with an AADT of 9,560. The highway now known as SR 149 between Morristown and New Athens has been a part of the State Highway System since 1912; the route was called SR 103 until 1922. By 1923, the Morristown-New Athens route was renumbered to SR 149. In 1930, the route was extended south to SR 147 just outside Belmont. In 1979, the route was extended from Belmont to Bellaire on essentially the route it runs today. From 1979 to 2010, SR 149 traveled on a less-direct route through Bellaire. At the intersection of 26th Street and Belmont Street, SR 149 headed into downtown Bellaire and traveled on Belmont, Crescent, Guernsey, 32nd, and Hamilton Streets. In 2010, ODOT completed a relocation of SR 149 to move the state highway off of the local streets in Bellaire.