High Quality Content by WIKIPEDIA articles! Denton County is a county located in the U.S. state of Texas. In 2000, its population was 432,976; in 2009 the estimated population had reached 628,300. Part of the Dallas – Fort Worth Metroplex, it is one of the fastest-growing counties in the United States. The county seat is Denton. The county and the city are both named for John B. Denton, who was a preacher, lawyer, and soldier. It was founded in 1846.