Allen is located in Collin County, Texas, a northern suburb of Dallas. As of the 2010 census the city had a total population of 84,246. According to the City of Allen, Allen has a total area of 27.1 square miles. None of the area is covered with water except the small ponds scattered throughout the city. The median income for a household in the city in 2007 was $93,392, and the median income for a family was $100,736. The Allen Independent School District has 17 elementary schools, 3 middle schools, 1 freshman center, 1 Pat Dillard Special Achievement Center, and 1 high school (Allen High School). Allen ISD serves almost all of Allen.