Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Ogle County is a county located in the U.S. state of Illinois. As of 2000, the population was 51,032. Its county seat is Oregon. The Rochelle Micropolitan Statistical Area includes all of Ogle County. Ogle County was formed in 1836 out of Jo Daviess and LaSalle Counties, and named in honor of Captain Joseph Ogle, a veteran of the Revolutionary War who came to Illinois in 1785. The county was divided three years later in 1839, when Lee County was formed.