St. Louis & St. Louis County
The City of St. Louis as well as St. Louis County are both significant karst regions, each of which have or have had an abundance of caves and a rich cave history.
Most of the caves and sinkholes within this region have been severly altered or in some cases destroyed by development.
Within the City of St. Louis many caves were historically used by beer brewers from the mid 19th century up through prohibition during the 1920's.
Within St. Louis County, caves which are still existent are typically found in and around residential areas, particularly in the areas of Oakville and Mehlville.
Over the years cavers associated with the St. Louis based Meramec Valley Grotto and MSS have been active in documenting and exploring the St. Louis area karst.