The City of Crystal Lake traces its origin to two separate communities which were established in the 1800s. Those communities were generally known as Nunda and Crystal Lake. In 1835, Ziba S. Beardsley had come to the shores of the lake and commented that the “waters were as clear as crystal”, thereby giving the lake its name.

The city of Crystal Lake has an unusual system of educational organization, as the high schools in the city are in a different school district than the middle schools and elementary schools. High schools in the city are run by Community High School District 155, which runs four high schools, including all three in the city of Crystal Lake. District 47 runs all middle schools and elementary schools in the city of Crystal Lake. The two districts are completely independent, having different budgets and administrations, including different superintendents. Prairie Grove Consolidated School District #46 also serves a portion of northeast Crystal Lake