is a city in and the county seat of Collin County, Texas, United States, and the second in population to Plano. In 2008, the U.S. Census Bureau estimated that the city's population was 115,620 The Census Bureau listed McKinney as the nation's fastest growing city from 2000 to 2003 and again in 2006, among cities with more than 50,000 people. In 2007 it was ranked second-fastest growing among cities with more than 100,000 people and in 2008 as third-fastest. McKinney is one of several fast-growing communities on the northeastern edge of the Dallas-Fort Worth Metroplex. Both the city and county are named after Collin McKinney, a signer of the Texas Declaration of Independence, and a congressman for the Red River district of the Republic of Texas.
According to the United States Census Bureau, the city has a total area of 58.5 square miles (151.5 km