What year was the Cumberland Gap Tunnel, one of two mountain vehicular tunnels in the United States, opened which extended U.S. 58 from Harrogate, Tennessee to Virginia Beach, Virginia?
U.S. Route 58: U.S. Route 58 is an east–west U.S. Highway that runs for 508 mi from U.S. Route 25E just northwest of Harrogate, Tennessee, to U.S. Route 60 in Virginia Beach, Virginia. U.S. Route 58:  Until 1996, when the Cumberland Gap Tunnel opened, US 58 ran only inside the commonwealth of Virginia. Cumberland Gap Tunnel:  It is one of only two mountain vehicular tunnels in the United States that cross a state line, the other being the East River Mountain Tunnel on Interstate 77 between Virginia and West Virginia.
1996