State Route 51

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Arizona 51 serves as a primary north-south route through the east central Phoenix area, as well as a reliever to I-17. Arizona 51 was the first urban (non-interstate) freeway built through Phoenix, and is unique in that the section from McDowell Rd to Glendale Ave was built by the City of Phoenix (not Arizona DOT) as a parkway - hence the original Squaw Peak Parkway name.

A freeway was first planned for the Arizona 51 corridor in 1960, however, freeway growth in Phoenix did not keep up with population growth for a multitude of reasons. Until 1966, I-17 was the only freeway through Phoenix. The Maricopa freeway (now Interstate 10) opened at this time to 40th street, and the Squaw Peak corridor held Interstate 510 as a route number through 1975 - which is the original source of the numbering for Arizona 51.

The Arizona DOT first purchased property in the Squaw Peak corridor in the mid-1960s, but stopped due to funding issues with regards to construction. After the Papago debacle, a fight erupted over routing the Squaw Peak freeway through Dreamy Draw, and the Arizona DOT focused its resources on projects outside of Phoenix. Phoenix mayor Margaret Hance, realizing traffic was becoming a major problem, admitted a freeway was not feasible in 1981, and changed the corridor to hold a parkway.

Planners set a route along 18th Street in 1982, drawing community opposition in the form of NEVER, a group of residents. NEVER, meaning "Neighbors Veto Expressway Routes," first questioned the traffic figures used to justify the route, leading to a sequence of events after the projections were justified:

  • March 29, 1983 - final alignment approved by Phoenix
  • April 5, 1983 - Ordinance passed allowing purchase of land
  • September 14, 1983 - Judge Moroney of Maricopa County deems vote (on alignment) legal, over petition of NEVER.
  • November 10, 1983 - Arizona Supreme Court rejects appeal of Moroney's decision
  • December 30, 1983 - NEVER files a lawsuit stating Arizona environmental laws were not followed. Lawsuit is rejected.

In the same time frame, NEVER put a Proposition on the February 7 ballot proposing a plan to build a continuation of 32nd Street through Phoenix Mountain Preserve, but completely disallowing the Squaw Peak Parkway. This measure was rejected by voters.

A citizen working group was commissioned to design Squaw Peak Parkway (the first mile), but all of their suggestions were rejected by the Phoenix City Council in January 1985, further angering local residents.

After this, Arizona 51 was constructed in segments from south to north. The last segment that connected the freeway to Arizona Loop 101 was opened to traffic on May 31, 2003.

Arizona 51 is named the Piestewa Freeway. It was known as the Squaw Peak Freeway until May 1, 2003, when it was renamed (along with Squaw Peak itself) in honor of Army Private First Class Lori Piestewa. Piestewa was the first Native American woman killed in combat as an American soldier; the Hopi died during the 2003 War in Iraq.

Arizona Route 51 North
Just after Exit 1 for McDowell Road, an interchange sequence sign appears for Thomas Road, Indian School Road and Highland Avenue. Photo taken 01/20/08.
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Just north of the Arizona 51/Arizona Loop 202/Interstate 10 interchange on the original parkway. The Mcdowell to Thomas section is the oldest section of Arizona 51, and opened July 21, 1986, as an at-grade parkway. In these photos, a reconstruction project is occurring between Interstate 10 and Shea Boulevard, adding a carpool lane through the entire section. Immediately north of the interchange, Arizona 51 is four lanes plus HOV lane, but will shed a lane at Thomas Road (Exit 2). Photo taken 01/20/08. Second photo taken 10/01/03.
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This Arizona DOT-standard sign assembly shows exit numbers; this exit is Thomas Road (Exit 2). Notice the raised sound walls. The Arizona DOT-installed cable barrier was removed in March 2003, which itself replaced the original City of Phoenix landscaping. Thomas was the last at-grade intersection on Squawk Peak Parkway, and the overpass opened on July 31, 1990. Not visible in this photo is the artwork under the overpass. Photo taken 01/20/08. Second photo taken 10/01/03.
Distance sign to Indian School Road, Highland Avenue/Camelback Road, and Bethany Home Road. Photo taken 01/20/08.
Advance signage for exit 3, Indian School Road. Use Exit 3 to reach the VA Hospital, as seen with this unusual landmark sign along the overhead. Photo taken 01/20/08.
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This former city of Phoenix non-standard sign shows what is coming for the next few miles of Arizona 51. As traffic shows, this road is very congested most hours of the day, and especially narrow. Notice the new soundwalls. Originally, the Parkway had a speed limit of 45 MPH, which was raised to 50 MPH in 1988, and 55 MPH when ADOT assumed control of the Parkway. This is Exit 3, Indian School Road. Photo taken 01/20/08. Second photo taken 10/01/03.
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Exit 4A featured another non-standard sign, but it is closer to Arizona DOT standards. When the second photograph was taken, Highland was closed due to the construction project. Highland serves Camelback Ave, a major thoroughfare and shopping area, and has only an exit from northbound Arizona 51. Southbound Arizona 51 traffic to the Camelback area uses Coulter Ave. Photo taken 01/20/08. Second photo taken 10/01/03.
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This view shows the narrow corridor, short Highland off-ramp, and entry into the Camelback Corridor at Exit 4A. Between Highland and Coulter, Arizona 51 takes a very urban feel, similar to Interstate 5 through the S-Curve in San Diego. The narrow corridor was necessitated by high land values in this area and dense development. Photo taken 01/20/08. Second photo taken 10/01/03.
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Mileage sign along northbound for Bethany Home Road, exit 4B. First photo taken January 20, 2008. Photo taken 01/20/08. Second photo taken 10/01/03.
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2 photos
Advance signage for exit 4B, Bethany Home Road. Notice how the original overhead sign was connected to the retaining wall, and the high multi-layered retaining wall. Bethany Home was one of the few original signals, and was designed as an overpass in original (1984) plans, but changed in 1988 to the current underpass. Photo taken 01/20/08. Second photo taken 10/01/03.
Bethany Home Road departs here as exit 4B. Traffic can only travel westbound on Bethany Home Road from here - eastbound traffic is restricted to local traffic only. This restriction was one of the concessions required to construct the freeway. Photo taken 01/20/08.
Distance sign to Glendale Avenue and Lincoln Drive, Northern Avenue and 32nd Street. Photo taken 01/20/08.
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After Bethany Home, the freeway widens as it approaches Glendale Road (Exit 5). Trucks were not allowed on Arizona 51 from 1989-1993, to appease residents, but ADOT has a policy of not restricting truck traffic. Photo taken 01/20/08. Second photo taken 10/01/03.
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Exit 5, Glendale Avenue, marks the end of city of Phoenix road and the transition to an Arizona DOT-constructed highway. The Thomas to Glendale section opened in 1990, with the whole road turned over to ADOT maintenance in 1993. Between July 1988 and 1990, the section of Interstate 10 between Arizona 51 and Interstate 17 was signed as Arizona 51, until the gap between existing Interstate 10 (at the Stack interchange) and 7th Street was constructed - which was designed not to confuse through traffic and keep that traffic on Interstate 17. Photo taken 01/20/08. Second photo taken 10/01/03.
Advance signage for exit 7, Northern Avenue. Photo taken 01/20/08.
Distance sign to Northern Avenue, 32nd Street and Shea Blvd. Photo taken 01/20/08.
Now on Arizona DOT-standard road, SR 51 reaches Exit 7 for Northern Avenue at the Phoenix Mountains Preserve. The Preserve is home of original namesake Squaw Peak, which was later renamed Piestewa Peak). SR 51 replaced Northern Avenue through Dreamy Draw, and the freeway widens to ten lanes through this important gap in the mountains. This section of SR 51 to Loop 101 was added to Squaw Peak Parkway in 1985, but it was part of the original 1960 freeway system. Arizona DOT took responsibility for construction after the 1985 freeway plan was passed by voters. Photo taken 01/20/08.
Arizona 51 turns to follow the original alignment of Northern Avenue through Dreamy Draw. The two peaks seen here are unnamed. Photo taken 01/20/08.
Distance sign to 32nd Street, Shea Blvd and Cactus Road. Photo taken 01/20/08.
Continuing past most of the way through Dreamy Draw, SR 51 approaches 32nd Street. Photo taken 01/20/08.
Through the Arizona DOT-constructed section, pedestrian overpasses have been artistically designed. This one is just before 32nd Street going northbound. Photo taken 10/01/03.
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2 photos
At 32nd Street, one of the lanes exits and Arizona 51 turns north. Due to the proximity of 32nd Street and Shea, 32nd Street only has an exit northbound and an entrance southbound. Photo taken 01/20/08. Second photo taken 10/01/03.
Distance sign to Shea Blvd, Cactus Road and Thunderbird Road. Photo taken 01/20/08.
Exit 9, Shea Blvd, departs from Arizona 51 here. Shea marks the limits of 1996 construction, and the limits of the 2003 HOV lane. Notice from here north how the freeway is built to full Arizona DOT standard, with a carpool lane being added in the median. The original plan was to run Arizona 51 along 32nd Street, but it was changed after a citizen group recommended a 34th Street alignment to Arizona DOT and the City of Phoenix. Photo taken 01/20/08.
The next exit north of Shea is Cactus Rd. This shot also shows another feature of the 2003 reconstruction project, resurfacing of the original concrete road with a rubberized asphalt overlay. The overlay features asphalt made from recycled tires, and reduces freeway noise by three to four decibels. The rubberized asphalt program was completed in 2006. Photo taken 01/20/08.
Cactus Road departs here, as exit 10. Photo taken 01/20/08.
Advance signage for Thunderbird Road. This section of Arizona 51 is less heavily trafficked, and features the standard three lanes plus an auxiliary lane between exits at this point. Here you can also see the freeway is below grade, with sound walls at the top of the grade, standard construction for new Valley freeways. Photo taken 01/20/08.
Thunderbird Road departs here, as exit 11. Photo taken 01/20/08.
SR 51 advances 0.75 mile north from Cactus Road with three through lanes to Greenway. Photo taken 01/20/08.
Advance signage for Greenway Road and upcoming exits. This shows the grid system is spaced exactly a mile apart, conforming to USGS section lines. Photo taken 01/20/08.
The Greenway exit (Exit 12) passes beneath a stylized overpass, designed to represent the peaks of Phoenix. In the distance you can see the Greenway single point urban interchange (SPUI). Almost all exits on Arizona 51 are SPUI interchanges. Photo taken 01/20/08.
Advance signage for Bell Road, exit 13. Bell Road is a primary east-west arterial across the north valley. Photo taken 01/20/08.
Bell Road (Exit 13) was the terminus of Arizona 51 until May 31, 2003. Photo taken 01/20/08.
Advance signage for Union Hills Drive (Exit 14) and Arizona Loop 101 (Exit 15). Notice the new Loop 101 shield (new standard Black on White, not White on Blue) and rubberized asphalt. The overlay in this section was applied just before the freeway opened, and the overlay goes all the way along the Arizona Loop 101 exit ramps. Photo taken 01/20/08.
Union Hills Drive departs here as exit 14. Photo taken 01/20/08.
Just past Union Hills Drive, the last set of exits (exits 15A and 15B) connect Arizona 51 to Loop 101. The construction on the left side is part of the HOV project to allow a HOV connection between Arizona 51 northbound and Loop 101 eastbound. Photo taken 01/20/08.
Arizona 51 ends at Loop 101. There are no plans to extend Arizona 51 north of Loop 101. Photo taken 01/20/08.
Arizona Route 51 scenes
View of Arizona 51 signage from the Cactus Road interchange looking eastbound on Cactus Road. Photo taken 03/01/03.

Photo Credits:

  • 03/01/03 by AARoads.
  • 10/01/03 by Kevin Trinkle.
  • 01/20/08 by Kevin Trinkle.

Connect with:
Interstate 10
Loop 101
Loop 202

Page Updated 01-21-2008.