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.

Major habitat types on the refuge include hardwood forest, agricultural land, grazing units, brushland, wetlands, and lakes.

The refuge provides significant resting areas for migratory birds utilizing the Mississippi Flyway.

Industrial activities on the refuge range from manufacturing and storage facilities to administrative offices.

Many buildings now housing industries were used in the manufacturing of high explosives during World War II, and they are still used for military ordnance production today.