What it means
The 51 is State Route 51, the Piestewa Freeway: 16.7 miles of highway that start at the Mini Stack interchange with I-10 and the Loop 202 near downtown Phoenix and run north, through the Dreamy Draw pass between Piestewa Peak and North Mountain, to the Loop 101 near Desert Ridge. It never enters Scottsdale. Scottsdale uses it anyway.
For the east side of the Valley, the 51 is the shortcut into central Phoenix. “Take Camelback to the 51” is how a Scottsdale local gets to the Biltmore, downtown or, by way of the 202, Sky Harbor when the 101 is a parking lot. From the resorts of the Camelback Corridor, the airport guide runs the route in reverse: the 202 to the 51 north, then east on Lincoln or Camelback. Locals say it the Southern California way, with the article, and most of them say “the 51” precisely because it saves them pronouncing Piestewa.
Driving times and alternatives are in getting around Scottsdale. This page is about the name.
Where you’ll meet it
Traffic reports, airport directions, the exits at Shea, Lincoln and Camelback, and the trailheads of the Phoenix Mountains Preserve that line it.
Where the word came from
The freeway is older than it looks. A 1955 federal plan for the Interstate system showed a spur running north from what became I-10 along roughly this route, and it was designated Interstate 510 before it was dropped. Arizona carried it in route logs from 1968 as State Route 510, and the City of Phoenix built the first five miles, from McDowell Road to Glendale Avenue, between 1986 and 1991. It was renumbered SR 51 in 1987, handed to the state in 1992, and extended north to the 101.
For its first decades it carried the name of the peak it passes, in a form that used squaw, a word widely regarded as a slur against Native American women; federal naming guidelines had long urged removing it from natural features. Then, on March 23, 2003, Army Spc. Lori Piestewa, a 23-year-old Hopi mother of two from Tuba City, was killed when her convoy from the 507th Maintenance Company was ambushed near Nasiriyah, Iraq. She was the first Native American woman known to die in combat in the U.S. military.
Governor Janet Napolitano pushed to rename the peak for her within weeks. In April 2003 the Arizona State Board on Geographic and Historic Names voted 5 to 1 to make it Piestewa Peak, and on May 1, 2003, the Arizona Transportation Board voted 5 to 2 to rename the freeway immediately. The signs changed; the habit of saying “the 51” got stronger.
What it is not
It is not in Scottsdale, and it is not the 101 or the 202, which are the loops that actually serve the city. It is also not the same as Piestewa Peak, the 2,610-foot summit beside it, which has its own trails and parking.
The fine print
The renaming was contested. Napolitano’s petition bypassed the usual procedures, which drew political criticism, and the federal government moved more slowly: the U.S. Board on Geographic Names requires five years after a person’s death before naming a feature for them, and it voted 11 to 2 on April 10, 2008, to make Piestewa Peak official on federal maps. The two dissenting members argued that Piestewa had no direct connection to the mountain. The board received about 1,300 comments, roughly two-thirds in favor.
The freeway kept growing. Widening between Shea Boulevard and the Loop 101 to add a carpool lane in each direction, plus ramps to the eastbound 101, was finished in the summer of 2008, and a new interchange at Black Mountain Boulevard opened in March 2016, extending the road past its old northern end. The whole route is on the National Highway System.
Lori Piestewa’s name also appears on Piestewa Hall at Fort Benning and on the annual Lori Piestewa National Native American Games. Her friend and fellow soldier Jessica Lynch has repeatedly said Piestewa was the real hero of the ambush.