 Planning on how to route the freeway over the Rocky Mountains began in the early 1960s . The US 6 corridor crosses two passes : Loveland Pass , at an elevation of 11 @,@ 992 feet ( 3 @,@ 655 m ) and Vail Pass , at 10 @,@ 666 feet ( 3 @,@ 251 m ) . Engineers recommended tunneling under Loveland Pass to bypass the steep grades and hairpin curves required to navigate US 6 . The project was originally called the Straight Creek Tunnel , after the waterway that runs along the western approach . The tunnel was later renamed the Eisenhower – Johnson Memorial Tunnel , after U.S. President Dwight D. Eisenhower and Colorado Governor Edwin C. Johnson . 
