Interstate 17

Interstate 17 is known as the Black Canyon Freeway from the northern end of the Phoenix Metropolitan Area to a point 2.2 miles (3.5 km) south of The Stack interchange with Interstate 10 northwest of Downtown Phoenix. (It is accompanied by frontage roads for most of this portion, and they carry the Black Canyon Highway name to distinguish from the freeway status.) At the Durango Curve southwest of downtown, between the 19th Avenue and Buckeye Road interchanges, it picks up the designation Maricopa Freeway all the way to the southern terminus at the second Interstate 10 junction. It is one of the metropolitan area's primary freeways.[1][3] It has two interchanges with Interstate 10 in Phoenix.

I-17 has the unusual distinction of starting at approximately milepost 194 instead of at milepost zero. This is a holdover from Arizona's old system of marking mileposts, where a branching route would continue the milepost numbering of its original host, instead of starting over at zero. Interstate 17 inherited its milepost locations from SR 69, which the freeway replaced between Phoenix and Cordes Junction. SR 69's mileposting was such that it coincided with US 89's mileposting, which was 201.6 where the two routes intersected. When I-17 was constructed, the existing mileposting for SR 69 was retained.[1][3]

I-17 is closed to bicycles and pedestrians south of Anthem Way (exit 229) in the Anthem area, but is open to them north of this point.

• 
  "The Stack", intersection of Interstate 10 and I-17. Looking north up I-17, downtown Phoenix.
• 
  Southern terminus at I-10 in Phoenix
• 
  View of the Red Rocks of Sedona from I-17, just south of Munds Park
• 
  Interstate 17 near Flagstaff
• 
  Northern terminus at I-40 in Flagstaff

In 1936, SR 69 was established as a state route from Phoenix north to Prescott.[4][5] The road was completed by 1940 to Prescott. In 1954, a new route north to Flagstaff was established as SR 79. By 1961, the roadway from Phoenix to Flagstaff had been established, but not to Interstate standards.[6] By 1971, I-17 had been completed from Phoenix northward to Camp Verde where a short stretch had not been completed to standards. The stretch from SR 279 north to SR 179 was also complete. The largest section yet to be completed was from SR 179 north to Flagstaff. This segment was still just a two-lane roadway, but it did have full traffic interchanges built at crossroads. The portion from I-40 south to the Flagstaff Municipal Airport had been completed by this time.[7]

The existing interchange with Happy Valley Road in Phoenix is currently being converted to a diverging diamond interchange (DDI). The project is projected to be finished in the fall of 2020.[8]

• Roads and freeways in metropolitan Phoenix
• Interstate 19

Wikimedia Commons has media related to Interstate 17.

• I-17 at ArizonaRoads.com
• Google Maps I-17