The Chain O'Lakes is a waterway system in northeast Illinois composed of 15 lakes connected by the Fox River and man-made channels. Encompassing more than 7,100 acres (29 km2) of water, 488 miles (785 km) of shoreline and 45 miles (72 km) of river, the Chain is the busiest inland recreational waterway per acre in the United States. Located on the border of Lake County and McHenry County, about an hour's drive from the cities of Chicago, Milwaukee, and Rockford, the lakes are popular with boaters and fishermen, drawing weekend crowds of 30,000 and holiday crowds of 100,000 people. Chain O'Lakes State Park borders three lakes at the northwest corner of the system. The Fox Waterway Agency, a special local governing body, is responsible for oversight of the Chain O'Lakes.