Lake County is a county located in the U.S. state of Indiana. In 2020, its population was 498,700, making it Indiana's second-most populous county. The county seat is Crown Point. The county is part of Northwest Indiana and the Chicago metropolitan area, and contains a mix of urban, suburban and rural areas. It is bordered on the north by Lake Michigan and contains a portion of the Indiana Dunes. It includes Marktown, Clayton Mark's planned worker community in East Chicago.