Sinoe is one of Liberia's 15 counties and it has 17 districts. Greenville is the county's capital. As of the 2008 Census, it had a population of 104,932, making it one of the least populous counties in Liberia. As it is also Liberia's third-largest county in terms of area, it is accordingly the second least dense in terms of population density after Gbarpolu County.