Highway 131 was a straight rural highway, located west of Barrie's suburban fringe, though since then those suburbs have grown out to reach the former highway. Otherwise, the highway is abutted by the occasional farm and surrounded by several forests.
Highway 131 began at an intersection with Highway 27 (Essa Road), travelling north through the outskirts of Barrie. Although the city of 125,000 residents lay immediately east of the highway, Highway 131 was a two lane road throughout its length. North of Highway 27, the route travelled north through farmland, then west of the suburb of Holly. North of Mapleview Drive, the route entered a forested area. After travelling through a valley, the highway met Ardagh Road. It crossed the newly commissioned Barrie Collingwood Railway and shortly thereafter ended at Highway 90 (Dunlop Street), which travelled east to Barrie and west to Angus and CFB Borden.
On January 1, 1998, as part of the second round of Mass downloading, the MTO transferred responsibility for the maintenance and signing of the route to the County of Simcoe and City of Barrie. The route was quickly redesignated as Simcoe County Road 27; the former route of Highway 27 into Barrie is now known as Essa Street.