Spanning 8.2 miles (13.2 km), it serves as an east/west rural connector, connecting the town of Newton on SR-23 with the city of Smithfield on US-91 in Cache County.

[3] Beginning as an extension of Main Street (SR-23), it travels southeast about 1.1 miles (1.8 km) before turning due east,[3] crossing a northern arm of Cutler Reservoir and passing the town of Amalga.

From there, the route continues to the east and enters the city of Smithfield on 100 North, where it ends at its intersection with Main Street (US-91).

[9] As a result, State Route 218 was shortened by approximately 1 mile (1.6 km), as it now started on the east end of the town.

[2] Save for a minor realignment west of Smithfield to utilize a new bridge over the Bear River built in 1959,[2][10] the route has remained unchanged since.