Interurban Trail South, Rail trail in Washington, United States.

Interurban Trail South is a partially paved 14-mile (23 km) recreational trail for non-motorized use, running from Tukwila to Pacific and passing through Kent, Auburn and Algona. It occupies the abandoned Puget Sound Electric Railway corridor and connects to the Green River Trail. Paved segments in Edgewood, Milton and Fife opened in 2023 but are not yet linked to the main Tukwila–Pacific line.

This corridor follows the former route of the Puget Sound Electric Railway, which operated electric trolley service connecting Seattle and Tacoma from 1902 to 1928. After the railway closed, the right-of-way was gradually developed into a recreational trail.

The trail follows the abandoned Puget Sound Electric Railway corridor, and its southern section links to the Green River Trail. A planned connection to the Foothills Trail would let users continue south through Sumner and Puyallup toward South Prairie. The name Interurban recalls the electric line that once ran between Seattle and Tacoma.

The northern access point is located at Fort Dent Park, which is easily reached from Interstate 5 Exit 156. The southern end connects near Pacific, accessible by way of Highway 18.

Along the path, visitors can spot views of Mount Rainier while traveling through agricultural areas. The route also passes near Emerald Downs racetrack, a local landmark that adds character to the ride.