In 1939, the Rio Grande Valley Livestock Show and Agricultural Exposition, the foundation of today’s Show, was organized as a project of the Mercedes Chamber of Commerce. The first Show was held in 1940 on the grounds of a local livestock sales yard with improvised pens and lean-to sheds. The Show continued to be held on this same property until 1949 when it moved to its present location. In 1947, the Show was incorporated and chartered as a non-profit educational organization with a Board of Directors representing all of the four southmost counties of Texas.