Union Pacific controls all long-distance freight tracks into the county, though the Utah Railway, BNSF, and Salt Lake, Garfield, and Western have long-standing trackage rights. The Salt Lake City Southern and Savage Bingham and Garfield railroads operate totally within the county. All four major entrances to the Salt Lake Valley once carried rail traffic, but only railroads at the north, south, and west entrances to the valley exist today as the line in Parley's Canyon was never built to high standards and was covered by Interstate 80 in the mid-20th century. All three of these entrances carry passenger trains as well as freight.