Eisenhower Tunnel West Portal, Colorado

Located at 11,158 feet above sea level, the Eisenhower Tunnel is the highest vehicular tunnel in the nation's Interstate System. When it opened in 1979, it was considered the highest vehicular tunnel in the world. The 1.7-mile-long tunnel has two bores, one for the eastbound traffic (known as the Johnson tunnel), and one for westbound traffic of Interstate 70. It passes underneath the Continental Divide, the line which separates the nation into Atlantic and Pacific watersheds.