Editing Interstate 17 (section)

==History==

The I-17 corridor roughly follows the first stagecoach route through the Black Canyon, established in 1878 between Cañon (now Black Canyon City) and Prescott. A later highway through White Spar from Wickenburg to Yarnell was improved in 1925 and incorporated into US&nbsp;89 in 1926.<ref name="ADOTBlog-History">{{cite news |last=Corbett |first=Peter |date=September 21, 2018 |title=How the I-17 Black Canyon Freeway evolved from stage route to modern highway |url=https://azdot.gov/adot-blog/how-i-17-black-canyon-freeway-evolved-stage-route-modern-highway |work=ADOT Blog |publisher=Arizona Department of Transportation |accessdate=November 6, 2022}}</ref>

In 1936, SR&nbsp;69 was established as a state route from Phoenix north to [[Prescott, Arizona|Prescott]].<ref name="1938 map">{{cite map|publisher=[[Rand McNally]]|title=Arizona and New Mexico Road Map|year=1938|url=http://www.arizonaroads.com/maps/index.html|access-date=November 27, 2011}}</ref><ref>{{cite web|url=http://www.azhighwaydata.com/resolutions/?syear=&submit1=Submit&eyear=&crc=3&rtnum=69&page=4|author=Arizona Department of Transportation|author-link=Arizona Department of Transportation|access-date=April 22, 2008|title=ADOT Right-of-Way Resolution 1936-P-624}}</ref> The road was completed by 1940 to Prescott. In 1954, a new route north to Flagstaff was established as SR&nbsp;79. In May 1956, the Black Canyon Highway from Phoenix to Flagstaff was completed,<ref name="ADOTBlog-History"/> but not to Interstate standards.<ref name="1961 map">{{cite map |publisher=[[Rand McNally]] |title=State Highway Department Road Map of Arizona |year=1961 |url=http://www.arizonaroads.com/maps/index.html |access-date=November 27, 2011}}</ref> It was incorporated into the new [[Interstate Highway System]], established by the federal government later that year, and designated as part of I-17.<ref name="ADOTBlog-History"/>

The first interchange on the Black Canyon Freeway was built in 1950 west of downtown Phoenix and was extended to Grand Avenue in 1957.<ref name="AZ-First">{{cite news |last=Nothaft |first=Mark |date=February 21, 2017 |title=Which freeway came first in the Valley? |url=https://www.azcentral.com/story/news/local/phoenix-contributor/2017/02/21/which-freeway-came-first-valley/97871258/ |work=[[The Arizona Republic]] |accessdate=November 6, 2022}}</ref><ref name="ADOTBlog-History"/> The freeway was extended to McDowell Road by 1971 and out of the Phoenix suburbs by 1974, at a cost of $33&nbsp;million.<ref name="AZ-First"/> 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 [[Arizona State Route 279|SR&nbsp;279]] (now [[Arizona State Route 260|SR&nbsp;260]]) north to [[Arizona State Route 179|SR&nbsp;179]] was also complete. The largest section yet to be completed was from SR&nbsp;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.<ref name="1971 map">{{cite map |publisher=Arizona State Highway Department |title=State Highway Department Road Map of Arizona |year=1971 |url=http://www.arizonaroads.com/maps/index.html |access-date=November 27, 2011}}</ref> The final section of I-17, near Camp Verde and Montezuma Castle, began construction in February 1977 and opened to traffic in August 1978.<ref name="ADOTBlog-History"/><ref>{{cite news |date=May 18, 1978 |title=Last Link of I-17 To Open in August |page=15 |work=[[The Arizona Republic]] |url=https://www.newspapers.com/clip/112675527/last-link-of-i-17-to-open-in-august/ |via=[[Newspapers.com]] |accessdate=November 6, 2022}}</ref>

In 1993, officials in Arizona proposed an extension of I-17 to connect with [[Interstate 15 in Utah|I-15]] in [[Utah]].<ref>{{cite news|url=https://www.deseret.com/1993/1/2/19024583/arizona-officials-seek-extension-of-i-17-into-utah|title=Arizona officials seek extension of I-17 into Utah|date=January 2, 1993|agency=[[Associated Press]]|publisher=[[Deseret News]]|access-date=January 27, 2021}}</ref>{{Clarify|date=February 2021}}

The existing interchange with Happy Valley Road in Phoenix was converted to a [[diverging diamond interchange]] (DDI). The project was finished in the fall of 2020.<ref>{{Cite web|url=https://www.azdot.gov/projects/central-district-projects/i-17-ti-reconstruction-happy-valley-rd-and-pinnacle-peak-rd/happy-valley-rd|title=Happy Valley Road|website=www.azdot.gov|access-date=2019-08-26}}</ref>

Due to increasing weekend traffic on I-17 between the Phoenix area and northern Arizona, primarily between Phoenix in the south, and Sedona, Flagstaff, and the Grand Canyon in the north, ADOT started plans to widen a {{convert|34|mi|km|adj=on}} section of four-lane freeway between Anthem and the Sunset Point Rest Area in 2018.<ref name="improve">{{Cite web |title=Connecting Arizona - Improving I-17 |publisher = Arizona Department of Transportation |url=https://www.improvingi17.com/}}</ref> In 2021, the design was chosen, with a standard third general-purpose lane set to be added in both directions between Anthem and Black Canyon City, but due to the mountainous topography north of Black Canyon City to Sunset Point, two flex lanes will be added in a separate carriageway next to the existing southbound lanes.<ref name="widening" /> The lanes will be allocated depending on whichever direction has the most traffic, generally this will be northbound traffic from Monday through Saturday, and southbound traffic on Sundays. A combination of six different safety systems (vehicle arresting barriers, automated arm gates, concrete barriers, steel gates, dynamic messaging signs, and cameras) will control access to these lanes.<ref name="flex">{{Cite web |title=Connecting Arizona - Improving I-17 - Flex Lanes |publisher = Arizona Department of Transportation I-17 Improvements |url=https://www.improvingi17.com/flex-lanes/}}</ref> Construction began in 2022 and in May 2025, the additional lanes from Anthem to Black Canyon City opened.<ref name="abc memorial day">{{Cite web |last=Bontke |first=Jordan |title=Third lane on I-17 north of Phoenix opens ahead of Memorial Day weekend |website=ABC 15 Arizona |url=https://www.abc15.com/news/operation-safe-roads/i-17-opens-third-lane-ahead-of-memorial-day-weekend |date=May 22, 2025}}</ref><ref name="adot memorial day">{{Cite press release |title=New I-17 lanes open between Anthem and Black Canyon City |publisher=Arizona Department of Transportation |url=https://azdot.gov/news/new-i-17-lanes-open-between-anthem-and-black-canyon-city |date=May 22, 2025}}</ref> The flex lanes are scheduled to be completed by the end of 2025.<ref name="improve" /><ref name="girder" />