About This Place
Johnston City is a city in Williamson County, Illinois, United States. The population was 3,557 at the 2000 census.
Johnston City is located at 37°49′15″N 88°55′39″W / 37.820747°N 88.927529°W / 37.820747; -88.927529.
According to the United States Census Bureau, the city has a total area of 2.0 square miles (5.2 km²), of which, 2.0 square miles (5.1 km²) of it is land and 0.1 square miles (0.2 km²) of it (2.99%) is water.