Gages Lake is a census-designated place (CDP) in Warren Township, Lake County, Illinois, United States. The population was 10,198 at the 2010 census.
The CDP is located in central Lake County at 42°21′7″N 87°58′59″W (42.3520277, -87.9829260). It is in southwestern Warren Township and is bordered to the north and east by the village of Gurnee, to the northwest by the village of Third Lake, and to the west by the village of Grayslake. The water body of Gages Lake is in the western part of the CDP and extends into the village of Third Lake. The CDP includes the communities of Idlewild and Wildwood.
U.S. Route 45 runs along the western edge of the community, leading south 6 miles (10 km) to Mundelein and north 15 miles (24 km) to Bristol, Wisconsin. Illinois Route 120 runs along the southern edge, leading east 8 miles (13 km) to Waukegan and west 4 miles (6 km) to Hainesville. The CDP is 42 miles (68 km) northwest of downtown Chicago.
According to the United States Census Bureau, the Gages Lake CDP has a total area of 3.2 square miles (8.2 km2), of which 3.0 square miles (7.7 km2) are land and 0.2 square miles (0.5 km2), or 6.00%, are water.
As of the census of 2000, there were 10,415 people, 3,725 households, and 2,793 families residing in the CDP. The population density was 3,374.0 people per square mile (1,301.4/km2). There were 3,829 housing units at an average density of 1,240.4/sq mi (478.4/km2).