| DeKalb County Illinois Cities/Towns - Cortland, DeKalb, Genoa, Hinckley, Kingston, Kirkland, Lee, Malta, Maple Rock, Sandwich, Shabbona, Somonauk, Sycamore (County Seat), Waterman |
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Your Ad Here DeKalb County is a county located in the U.S. state of Illinois. As of 2007, the population is estimated at 103,729. Its county seat is Sycamore. History DeKalb County was formed in 1837. The County was named in honor of Johann de Kalb a German (Bavarian) hero of the American Revolutionary War. Kalb was with Gen. Washington at Valley Forge. He was killed at the Battle of Camden. ![]() |