It is planned as a controlled-access freeway to relieve heavy traffic congestion experienced along Interstate 10 in the area.

State Route 50, also known as the Paradise Parkway, was a proposed urban freeway through Glendale and Phoenix.

Originally proposed in 1968 as SR 317,[1] the freeway would have run east to west, connecting the future State Route 51 and Loop 101, while running roughly parallel to, and 4 miles (6.4 km) north of, I-10 in the vicinity of Camelback Road.

[2] As the proposed freeway would have crossed through largely developed land and densely populated neighborhoods, it proved to be both extremely expensive and highly unpopular.

The route was eventually struck from state planning maps[3] and all land acquired for right-of-way was subsequently sold, the funds being used to pay for other transportation projects.

This would have established concurrencies with US 30, US 40S, US 50, US 550, US 450 and US 66 as well as replacing US 666 between Cortez, Colorado and Gallup, New Mexico.

US 87 would have been concurrent with US 180 west to Safford, where it would have then replaced SR 81 (now US 191) through Willcox to a junction near Elfrida.

US 87W would have then replaced the entirety of SR 82 between Tombstone Junction and Nogales, establishing a western terminus at US 89.

[7] In an ironic twist, US 666 was extended into Arizona in 1942 along the previously proposed US 87 and US 87E to Douglas.

It was proposed, starting in the town of St. Johns and would have ended at the New Mexico state line.

It did show on state maps during the early 1970s, but the route disappeared in the mid to late '70s.