It went through some iterations up north early on, but the 147 miles of Interstate 17 running between Phoenix and Flagstaff that has long become part of Arizona’s identity has a big birthday this year.
Also known as the Black Canyon Freeway, I-17 was the first freeway in Phoenix when it opened 75 years ago in 1950. The north-south running lanes first started west of downtown Phoenix near Durango Street.
With the number of miles traveled each year on Arizona roads more than tripling between 1945 and 1955, as noted in ADOT’s Arizona Transportation History, the volume necessitated a freeway system for Phoenix. Beginning in 1950 with the Black Canyon Freeway, its purpose was not only to relieve rush-hour congestion in the city but to increase the capacity of State Routes 69 and 79 up north, which connected the Salt River Valley to the Verde Valley and Flagstaff.
