Built in 1943 as a railroad tunnel to connect inland Bear Valley with the small port city of Whittier, the Anton Anderson Memorial Tunnel was built beneath Maynard Mountain and is now not only the longest highway tunnel in North America, but also one of a few to service both rail cars and automobiles.

The remarkably tight, one-lane highway running through the tunnel originally only serviced rail traffic through its two and half mile length. The passage was constructed by the military during World War II to act as Alaska’s main supply route for goods arriving in the protected deep-water port in Whittier. When the military abandoned Whittier in the 1960s, the tunnel was made a part of the Alaska highway system and given a massive overhaul. The traditional tracks on sleepers were replaced with a solid concrete path that brought the rails flush with the road surface, so that cars could now use the long tunnel as well, making it one of the few dual-use tunnels in the country.

To facilitate this new civilian purpose, a number of safe houses were built along the tunnel in case of wrecks or natural disasters, as well as a three-foot-wide emergency sidewalk and emergency turnouts for vehicles that make travel through the expanse seem just a touch less claustrophobic. To maintain air quality in the underground tunnel, high-power reversible jet fans are placed at each end of the tunnel, forcing fresh air through a series of vents along the road.

Given that the road is only able to accommodate a single lane of traffic, going only one way at any given time, the Anton Anderson Memorial Tunnel is now controlled by a sophisticated computer system that directs traffic at regular intervals, with cars heading to Whittier leaving on the half hour and cars leaving Whittier leaving on the hour. Trains, while infrequent, can cause delays in motor vehicle traffic. Bicycle and foot traffic are strictly prohibited in the tunnel.