Wylie is a city and northeastern suburb of Dallas, that was once solely located in Collin County, but now extends into neighboring Dallas and Rockwall counties in the U.S. state of Texas. It is located on State Route 78 about 24 miles (39 km) northeast of central Dallas and centrally located between nearby Lavon Lake and Lake Ray Hubbard.

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.