What it means
The grid is how the Valley tells you where you are. Nearly every major road runs north-south or east-west, the big ones a mile apart, and the address numbers count outward from a single corner in downtown Phoenix: Central Avenue and Washington Street. Scottsdale, despite having its own name on everything, uses that same grid. So an address in Scottsdale is also a set of coordinates. “7014 East” is about eight and three-quarter miles east of Central. “15000 North,” the address of the Scottsdale Airport, is up in the Airpark.
Locals talk in grid shorthand without noticing. “It’s at 64th and Camelback” names a corner as precisely as a pin; “the 7200 block” is Scottsdale Road; and “a mile east” means one arterial over, where Hayden Road runs. Newcomers learn it in a week, which is the point of the first-year guide and one reason the getting-around guide can describe the city in three north-south roads.
Where you’ll meet it
On every street sign, where the hundred-block number sits beside the name; on resort, trailhead and restaurant addresses; in the numbered streets of south Scottsdale, like 68th Street; and in directions given by anyone who has lived here more than a year.
Where the word came from
The grid is older than the cities that use it. The arterial roads sit a mile apart because they follow the one-mile section lines of the federal land survey, which divided the desert into square-mile sections measured from an initial point near the junction of the Gila and Salt rivers, by today’s Phoenix Raceway. The major roads grew up along those section lines, which is why they are so evenly spaced.
The address numbering came from Phoenix. Its townsite planners first gave east-west streets presidents’ names and north-south streets Native American names, but the north-south streets were soon changed to numbers: numbered Avenues west of Central and numbered Streets east. As the city spread, the numbering spread with it, and Scottsdale, among other neighbors, uses the same count from Central and Washington. Scottsdale’s main roads carry names rather than numbers, which is why Scottsdale Road is not called 72nd Street, but the numbering beneath them is the same.
Maricopa County’s addressing rules, effective 2009, spell out the pattern. East of the zero point, numbered roads take the suffixes Street, Place and Way in an easterly direction, with every eighth of a mile a Street; west of it, Avenue, Drive and Lane. Hundred-blocks fall every eighth of a mile east and west, which is where the 800-numbers-per-mile rule comes from. On north-south streets the odd numbers are on the east side; on east-west streets, the south side.
Nobody coined “the grid” for the Valley. It is simply what locals call the system, usually right before explaining it to a visitor.
What it is not
The grid is not universal. Mesa counts from Center Street and Main Street, and Chandler runs its own system, so Broadway Road changes numbering as it crosses from Tempe into Mesa. And it is not perfectly regular in the north-south direction, where the old central blocks were drawn to different lengths.
The fine print
East and west, the math is clean: divide the hundreds by eight to get miles from Central. Scottsdale Road at 7200 East is nine miles out. North and south, it is messier. The county’s own rules list exceptions in central Phoenix, where hundred-blocks between Camelback and Indian School, Indian School and Thomas, and Thomas and McDowell are drawn to different lengths, so a North number below Dunlap does not convert neatly into miles. In most of Scottsdale north of there, addresses climb steadily: the Airpark sits around 15000 North, and the numbers keep rising toward Carefree.
The grid also bends where the land does. Diagonal roads, curving subdivision streets and the Indian Bend Wash interrupt it, and the county numbers those on whichever grid axis fits best. The Salt River Pima-Maricopa Indian Community east of the 101 and the town of Paradise Valley to the west both sit on the same numbering, which is why an address can read “Scottsdale” and lie outside the city entirely; see is Scottsdale in Phoenix? and the entry on ZIP codes for that confusion.
The practical upshot: an East number tells you how far you are from downtown Phoenix, the grid tells you how to get anywhere in right angles, and a mile is one arterial, about two minutes without traffic and much longer on Scottsdale Road in February.