 SR 78 begins at an intersection with US 23 Business (Main Street) in the town of Appalachia.The state highway heads east and immediately turns north onto the old alignment of Main Street, which parallels US 23 Business.SR 78 crosses Callahan Creek and curves northwest onto Callahan Avenue to pass under US 23 Business, which crosses over the creek, the state highway, and a Norfolk Southern Railway spur line, formerly part of the Interstate Railroad, on a sweeping bridge.