The Interstate Railroad (reporting mark INT) was a railroad in the southwest part of the U.S. state of Virginia. It extended from the Clinchfield Railroad at Miller Yard in northeastern Scott County north and west to Appalachia and north to the main yard at Andover, with many branches to the north into the mountains. The company still exists as an operating subsidiary of the Norfolk Southern Corporation, but is operated as if it were a Norfolk Southern Railway line.
The Interstate Railroad generally followed the valleys of the Guest River and Powell River, with only one summit, at Norton, between those two rivers.
The railroad began at the Clinchfield Railroad's Miller Yard, along the Clinch River between Dungannon and Carfax. It started off paralleling the Clinchfield to the northeast until its crossing of the Guest River (the line between Scott County and Wise County). The Interstate crossed the Guest River and split away to the north, running first along its east shore and then along its west shore and through the short Swede Tunnel. The Interstate crossed the Guest River again, where the river turned west, and continued north through another tunnel to Maytown.