is a city in Maricopa and Yavapai counties in the U.S. state of Arizona. Located primarily in Maricopa County, it is a major suburb of Phoenix. According to 2006 Census Bureau estimates, the population of the city is 142,024. Peoria is currently the fourth largest city in the state of Arizona in terms of land area, and the ninth largest city in the state in terms of population. The city was named after Peoria, Illinois. (The word “Peoria” is a corruption of the Illini word for “prairie fire.” ) Peoria is now larger in population than its namesake. It is the spring training home of the San Diego Padres and Seattle Mariners who share the Peoria Sports Complex. In July 2008, Money Magazine listed Peoria in the "Top 100 Places to Live".
According to the United States Census Bureau, the city has a total area of 141.7 square miles (366.9 km²), of which, 138.2 square miles (358.0 km²) of it is land and 3.5 square miles (9.0 km²) of it (2.44%) is water.
Peoria has now annexed over and is in two counties Maricopa County and Yavapai County. It is technically the largest incorporated city in Yavapai County even though almost all of Peoria’s current population resides on the Maricopa side.
The Agua Fria River and New River are the only rivers that flow through Peoria. The Agua Fria River is usually dry due to the New Waddell Dam that hold back Lake Pleasant in the northern end of the city. The New River is usually dry due to flood control measures. There are multiple washes and creeks that flow through the city as well, one of the most significant is the Skunk Creek due to its trails and connectivity with nearby Glendale.
Peoria has many smaller mountains and hills in the northern end. Some include Sunrise Mountain, West Wing Mountain, East Wing Mountain, Calderwood Butte, Cholla Mountain, White Peak, Hieroglyphic Mountains, and Twin Buttes.
The street system of Peoria is based on the city of Phoenix traditional grid system, with most roads oriented either north-south or east-west. The zero point is in downtown Phoenix at Central Avenue and Washington Street. Since Peoria is always west of zero, its north-south numbered Streets are Avenues. Major arterial streets are spaced one mile (1.6 km) apart (until you are north of roughly Pinnacle Peak Road). The one-mile (1.6 km) blocks are divided into approximately 800 house numbers although this varies. 83rd Avenue, being 8300 West. The numbers in Phoenix start at Central Avenue at a half-mile increment, going west to 7th Avenue ½ mile from Central but considered the arterial. Then the numbers go to 19th (1 mile from 7th), 27th, 35th, 43rd, 51st, 59th, 67th (in many places Peoria’s eastern border), 75th, 83rd, 91st, 99th, and so on. In northern Peoria streets are more curvilinear and begin to not follow the north-south route due to rivers, mountains, and terrain challenges. The northern end of the city does still follow the alignment theory and still has blocking according to Phoenix.