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Williamson County Illinois Cities/Towns -
Bush, Cambria, Carterville, Colp, Corinth, Crainville, Creal Springs, Energy, Freeman Spur, Herrin, Hurst, Johnston City, Marion (County Seat), Pittsburg, Spillertown |
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Your Ad Here Williamson County is a county located in the U.S. state of Illinois. As of 2016, the population was 67,560. Its county seat is Marion. History Williamson County was formed on February 28, 1839. It was named for Williamson County, Tennessee. ![]() |