Effingham is a city in Effingham County, Illinois, United States. It is the county seat of Effingham County. Effingham has a broad range of restaurants, lodging, and shopping facilities. Effingham is also located on U.S. Highway 40, the historic National Road, which stretches from Cumberland, Maryland to East St. Louis, Illinois. According to the United States Census Bureau, the city has a total area of 8.7 square miles (23km2), of which, 8.7 square miles (23km2) of it is land and 0.1 square miles (0.26km2) of it (0.69%) is water.