The SODO Busway, also referred to as the E-3 Busway, is a 1.5-mile-long (2.4 km) busway in the SoDo neighborhood of Seattle, Washington. It has four stops, including two that connect to Link light rail stations, and functions as an extension of the Downtown Seattle Transit Tunnel, which was formerly used by buses. The busway is served by ten bus routes—seven King County Metro routes from southern King County and three Sound Transit Express routes from Pierce County.