Tarrant County is a county located in the U.S. state of Texas with a 2020 U.S. census population of 2,110,640, making it the third-most populous county in Texas and the 15th-most populous in the United States. Its county seat and largest city is Fort Worth. Tarrant County, one of 26 counties created out of the Peters Colony, was established in 1849 and organized the next year. It is named after Edward H. Tarrant, a lawyer, politician, and militia leader.