Massac County is a county located on the Ohio River in the state of Illinois, USA, in that portion of the state known locally as "Little Egypt". According to the 2010 census, it has a population of 15,429, which is an increase of 1.8% from 15,161 in 2000. Its county seat is Metropolis.
This area was occupied by various cultures of indigenous peoples for thousands of years before European contact. The most complex and last was that of the Mississippian culture, which built the complex mounds and plaza at the Kincaid Site (now a National Historic Landmark). They abandoned the site in about 1500, centuries before European contact.
Part of the Illinois Country was claimed by French explorers; this area was barely settled, with most French colonial villages close to the Mississippi River. During the French and Indian War against the British, the French built a fort here in 1757. It was named Fort Massac after Claude Louis d'Espinchal, Marquis de Massiac, the French Naval Minister. Massiac is a commune in Cantal, France. Although beginning to be settled by European Americans after the American Revolution, Massac County was formally organized on February 8, 1843, out of territory from both Johnson and Pope counties. In the mid-19th century, after the revolutions of 1848, the Midwest received many German immigrants. Their self-identified descendants today comprise nearly one-third of the population of the county.