Eisenhower Tunnel: The Highest Point on America's Interstates, Colorado

For most of history, crossing the Colorado Rockies west of Denver meant going over them. Travelers climbed mountain passes, including Loveland Pass, nearly 12,000 feet high at the Continental Divide, through snow, ice and switchbacks. When the federal government planned the Interstate Highway System, Colorado lobbied hard for a transcontinental route straight across the state. That meant finding a way through the Divide itself. The answer was a tunnel, and it was a long time coming. The project followed more than 50 years of discussion, planning and design. Construction on the first bore began on March 15, 1968, under the Divide between Loveland Basin on the east and the valley of Straight Creek on the west. During construction it was called the Straight Creek Tunnel. Crews drove 7,789 feet through rock, and the bore climbs gently westward at a 1.64 percent grade. That puts the east portal at 11,013 feet and the west portal at 11,158 feet. The westbound bore, named for President Dwight D. Eisenhower, opened on March 8, 1973. At first it had to carry traffic in both directions, one lane each way. Work on a second bore began on August 18, 1975, and it opened on December 21, 1979, named for Edwin C. Johnson, a former Colorado governor and U.S. senator who had championed an interstate across the state. Each bore is about 1.7 miles long. When the Eisenhower bore was dedicated, it was the highest vehicular tunnel in the world. Higher tunnels have been built since, but it remains the highest vehicular tunnel in the United States, the longest mountain tunnel on the Interstate system, and the highest point anywhere on the Interstate Highway System. The tunnel also serves a second purpose: it carries water diverted from the western side of the Continental Divide to the eastern side. The tunnel didn't replace the mountain pass entirely. Vehicles carrying hazardous materials are banned from the tunnel and still have to climb over Loveland Pass on U.S. 6, the same route travelers used before it existed. Every day, drivers on I-70 pass through it, more than two miles above sea level, and most never notice they've reached the highest point on the whole Interstate system.