Woodstock is a city in and the county seat of McHenry County, Illinois, United States. It is located 51 miles (82 km) northwest of Chicago, making it one of the city's outermost suburbs. Per the 2020 census, the population was 25,630. The city's historic downtown district and turn-of-the-century town square is anchored by the landmark Woodstock Opera House and the Old McHenry County Courthouse. In 2007, Woodstock was named one of the nation's Dozen Distinctive Destinations by the National Trust for Historic Preservation.