When Interstate 8 was built through Telegraph Pass in the 60's, engineers were faced with a challenge. They needed to keep the grades at less than 6 percent in both directions. Due to the terrain it was not possible to widen the existing U.S 80 highway to the width required for the freeway.
The solution was found by examining the previous routes through the Gila Mountains. The Eastbound route simply used the existing route of the U.S. 80 highway that had been built in 1948. The Westbound route was built to generally follow the alignment of the original 1928 U.S. 80 roadway. In order to keep the grade under 6 percent the road had to be straightened somewhat. The other issue was the 1928 alignment crossed over the 1948 alignment. This lead to the unusual arrangement of the Westbound lanes being to the South instead of the North.