The originally designated road along modern SR 26 was SR 29, running between Lafayette and US 31, with SR 26 being routed between Bloomington and Madison. In the mid-1920s the state of Indiana renumbered its state road system and the SR 26 designated was moved to its contemporary alignment. During the early 1930s the route was extended, with several segments of SR 26 added to the state system. The last major addition happen in the late 1930s between SR 9 and Hartford City. The entire roadway was paved in the 1960s. In December 2013, the Indiana Department of Transportation (INDOT) relinquished the road through West Lafayette and Lafayette to the two cities.