Crab Orchard is an unincorporated census-designated place east of Marion in Williamson County, Illinois, located along an old route of Illinois Route 13 now designated Crab Orchard Road.

The upper branches of Crab Orchard Creek which eventually feed into Crab Orchard Lake flow nearby and gave the community its name.

For a brief time during the Civil War, it was known as Erwinsville, which is the name in the original plat of the village.

The Crab Orchard post office was established 18 August 1853 and discontinued operations 15 May 1924.

The Crab Orchard Public Library District serves the area with its main library in Crab Orchard and satellite services at Pittsburg and Creal Springs.