Roxton is a city in Lamar County, Texas, United States. As of the 2010 census, the city population was 650, a figure which declined to 548 a…Roxton is a city in Lamar County, Texas, United States. As of the 2010 census, the city population was 650, a figure which declined to 548 as of 2020. According to the United States Census Bureau, the city has a total area of 0.9 square miles, of which 0.9 square miles is land and 1.14% is water.