Addison is an incorporated town in Dallas County, Texas, United States. The 2020 census population was 16,661. Addison is immediately north of Dallas. Addison and Flower Mound were the only two Texas municipalities labeled "towns" with a population greater than 10,000 at the 2010 census; since then the municipalities of Prosper and Trophy Club—also identifying as towns—have also exceeded 10,000 in population estimates.