Kendall County is a county in the U.S. state of Illinois, within the Chicago metropolitan area. According to the 2020 census, it has a population of 131,869. Its county seat is Yorkville, and its most populous municipality is Oswego. Kendall County is part of the Chicago metropolitan area and was the fastest-growing county in the United States between 2000 and 2010.
Kendall County was formed in 1841 out of LaSalle and Kane Counties. The county is named after Amos Kendall, who was the editor of the Frankfort, Kentucky, newspaper, and went on to be an important advisor to President Andrew Jackson. Kendall became the U.S. Postmaster General in 1835.