Farmersville is a city located in Collin County, Texas, United States. The population was 3,612 at the 2020 census, with the larger Census Co…Farmersville is a city located in Collin County, Texas, United States. The population was 3,612 at the 2020 census, with the larger Census County Division having a population of 12,344. Farmersville originated in 1849 as a settlement on the Jefferson-McKinney Road, and near Republic of Texas National Road - now known as US Highway 380 and Texas State Highway 78, respectively. The settlement was named by two of the original settlers - William Pickney Chapman & John Hendrex - after the chief occupation of many of the residents.