Grayslake is a village in Lake County, Illinois, United States. It is located in the Chicago metropolitan area, about 40 miles (64 km) north of Chicago's downtown, 14 miles (23 km) west of Lake Michigan, and 15 miles (24 km) south of the Wisconsin border. The village's population at the 2010 census was 20,957.
Grayslake is home to the College of Lake County, Grayslake North High School, Grayslake Central High School, the University Center of Lake County and the Lake County Fairgrounds. There are tentative plans to develop a lifestyle shopping center on the previous location of the Lake County Fairgrounds. At the south end of Grayslake, there are plans for a 641-acre (259 ha) development containing light industry, office space and residential space.
In 1840, Massachusetts-born William M. Gray settled along the then-unnamed Grays Lake. Other farmers trickled into the area in 1840s. Gray moved to Waukegan in 1845.
In 1880, the Wisconsin Central Railroad built a line from Fond du Lac, Wisconsin, to Chicago that passed by the east side of Grays Lake. In 1886, the railroad built a station there, naming it Grayslake. The village incorporated in 1895.
Grayslake is located at 42°20′54″N 88°1′57″W (42.348271, -88.032428), in central Lake County. Neighboring communities include Libertyville, Mundelein, Round Lake Park, Hainesville, Round Lake Beach, Lindenhurst, Third Lake, Gages Lake and Wildwood.