Peoria is a city located primarily in Maricopa County, Arizona, USA, with a small portion in Yavapai County. It is considered a major suburb of Phoenix. As of the 2000 census, the city had a total population of 108,364, but a July 1, 2002 Census estimate put the fast-growing suburb's population at 123,239, making it the tenth fastest-growing incorporated place in Arizona. 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. It is the spring training home of the Seattle Mariners, who share a facility with the San Diego Padres.