Texas's 3rd congressional district of the United States House of Representatives is in the suburban areas north and northeast of Dallas. It encompasses much of Collin County, including McKinney and Allen, as well as parts of Plano, Frisco, and Prosper. Additionally, the district includes all but the southern portion of Hunt County. The district is also home to a public four-year university, Texas A&M University-Commerce, as well as Collin College.

Collin County is located in the U.S. state of Texas. It is part of the Dallas-Fort Worth-Arlington metropolitan statistical area, and a small portion of the city of Dallas is in the county. At the 2020 United States census, the county's population is 1,064,465, making it the sixth-most populous county in Texas and the 43rd-largest county by population in the United States. Its county seat is McKinney.