Van Vleck is a census-designated place (CDP) in Matagorda County, Texas, United States. The population is one of the few areas with positive growth in Matagorda County. The 2010 census showed a 25% increase with 1,844 people (versus 1,411 at the 2000 census). Although near Bay City, TX the site of Van Vleck falls outside the ETJ of Bay City, TX and is regulated by county police and county ordinance.