Volo Bog State Natural Area in Lake County, Illinois, preserves Volo Bog, a rare wetland recognized in 1973 as Illinois’s only remaining open-water quaking bog. Formed from a glacial lake, the bog began changing about 6,000 years ago as sphagnum moss spread over the water, creating acidic conditions that supported distinctive plants such as leatherleaf, orchids, and tamarack. The surrounding wetlands, meadows, woodlands, marshes, prairie restoration areas, shrubland, and old fields are vital because they reveal visible plant succession and help sustain the bog. Threatened by development in the mid-20th century, the area was secured through conservation efforts and later expanded as a state preserve with public access and education.