Crystal Lake is a suburb of Chicago located in southeastern McHenry County in the northeastern part of the US state of Illinois. It is named after Crystal Lake, a lake located 1.6 miles (2.6 km) west-southwest of downtown Crystal Lake. Crystal Lake is about 45 miles northwest of Chicago.
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. Ziba Beardsley continued south to Naperville. In February 1836, the first white settlers, Beman and Polly Crandall and six of their ten children, came from New York State traveling to Crystal Lake in a covered wagon. Their original cabin was built in the vicinity of today's intersection of Virginia Street and Van Buren Street. Four of the Crandall children were born there. Najah Beardsley's family was the second to settle in the area; his grandson, William Beardsley, was the first white child born on the Crystal Lake prairie, on May 7, 1837.