Warren Township High School District 121 covers more than 53 square miles, and it has the largest high school enrollment in Lake County, located in northeastern Illinois, with more than 4,000 students. The district has students from all or part of the communities of Gurnee, Park City, Waukegan, Grayslake, Third Lake, Beach Park and unincorporated areas of Grandwood Park, Gages Lake, Wildwood, and Millburn.