Colorado's Eisenhower tunnel turns 50 and shows its age

March 8 marks 50 years since a 1.7-mile tunnel opened and connected Colorado east to west beneath the Continental Divide — a feat so spectacular it's easy to forget what it took to become a reality.

Driving the news: The first tunnel, now the westbound side and named for former President Eisenhower, opened March 8, 1973, amid huge fanfare that drew hundreds to the ceremony.

• The second bore, named for former Colorado governor and U.S. Senator Edwin Johnson and now the eastbound route, came six and a half years later.
• Before then, travelers took dangerous turns on U.S. 6 over Loveland Pass or U.S. 40 over Berthoud Pass to reach the Western Slope.

What they're saying: "There was a lot of blood, sweat and tears to get that tunnel open," Tamara Rollison at the Colorado Department of Transportation tells Axios Denver.

Why it matters: Now known as the Eisenhower-Johnson Memorial Tunnel, the Interstate 70 route serves as the lifeblood of the state's economy — and a chokepoint that makes it the bane of every traveler.

• Since it opened, roughly 434 million vehicles have traveled through the tunnels — an average of 35,427 a day in 2022.
• And even in 2007, its economic impact approached $1 billion.

Flashback: The project actually started 50 years prior to its completion with a "pioneer" tunnel under Loveland pass in 1941 and an exploratory drilling bore that began at the current site in 1963.

What's next: The tunnel is aging and requires $150 million in infrastructure upgrades, mostly in modernizing operations motorists don't see, state transportation officials say. So far, only $50 million has been allocated.

• The most visible project is the building of a massive new operations center on the west side of the tunnel.

Photo gallery: The history of the Eisenhower tunnel at 50 years