Tuscarora Mountain Tunnel is one of four original Pennsylvania Turnpike tunnels still in active use. A second tube was bored in the late 1960s to ease traffic conditions. The Tuscarora Mountain tunnels measure 1.1 miles (1.8 km) in length and are the second-longest active tunnels on the Pennsylvania Turnpike system. The 1.3-mile-long (2.1 km) Sideling Hill Tunnel is the longest overall, but was abandoned in 1968. Allegheny Mountain Tunnel is the longest in active use.