CLEAR CREEK COUNTY, Colo. (KDVR) — The iconic Eisenhower Tunnel that connects the eastern side of the Rocky Mountains to the Western Slope turned 50 years old on Wednesday.

On March 8, 1973, the Eisenhower Tunnel became the highest vehicular tunnel in the world sitting at an elevation of 11,112 feet. And while higher tunnels have been built since then, the Colorado Department of Transportation is celebrating 50 years of connecting Colorado.

To celebrate the big 5-0, here are five facts to tell your passengers the next time you travel through the tunnel:

  1. The tunnel was originally called the Straight Creek Tunnel before later being officially named the Eisenhower Memorial Bore. Straight Creek Tunnel was derived from the valley where the west portal is located. Imagine saying you’re headed through the Straight Creek!
  2. The construction took five years to complete when work began on March 15, 1968, and was completed on March 8, 1973.
  3. At the height of the construction, as many as 1,140 workers were employed in three shifts, 24 hours a day, six days a week. Now that is a long work schedule.
  4. The Eisenhower tunnel is 1.693 miles long. With a speed limit of 50 mph, it takes about two minutes to travel through without traffic. Are you one of the people that likes to hold their breath through the tunnel?
  5. The tunnel receives an average of 26 feet of snow from November to April. If you’ve ever ventured through Eisenhower in the winter, you know firsthand how snowy it gets.

Happy birthday Eisenhower Tunnel, here’s to 50 more years of connecting the country to the west.

CDOT will share more about the tunnel’s history and significance in a press conference at 1 p.m. You can watch the event live in the player above.