McKinney was founded on March 24, 1849. Both the city and the county were named for Collin McKinney, signer of the Texas Declaration of Independence, and a congressman for the Red River district of the Republic of Texas.
He was the author of a bill establishing counties in the northern part of the state. McKinney is Collin County’s second-largest city, after Plano. McKinney’s motto is “Unique by nature”.