High Quality Content by WIKIPEDIA articles! The Seattle Streetcar—South Lake Union Line (colloquially the South Lake Union Streetcar, South Lake Union Trolley, or S.L.U.T.) is a 1.3-mile (2.1 km) streetcar line connecting the South Lake Union neighborhood to Downtown Seattle, United States. Service began on December 12, 2007. Currently it is the only operational line of the developing Seattle Streetcar Network.