High Quality Content by WIKIPEDIA articles! High Quality Content by WIKIPEDIA articles! Houston County is a county located in the U.S. state of Tennessee. As of 2000, the population was 8,088. The 2006 Census Estimate placed the population at 8,076. Its county seat is Erin. According to the U.S. Census Bureau, the county has a total area of 206.92 square miles (535.92 km²), of which, 200.21 square miles (518.54 km²) of it is land and 6.71 square miles (17.38 km²) of it (3.24%) is water.