Crab Orchard National Wildlife Refuge is a 43,890 acre (180 km²) National Wildlife Refuge primarily in southwestern Williamson County, but with small extensions into adjacent eastern Jackson and northeastern Union counties of southern Illinois, in the United States. Its land and water contain a wide diversity of flora and fauna. It centers on Crab Orchard Lake. Major habitat types on the refuge include hardwood forest, agricultural land, grazing units, brushland, wetlands, and lakes.