Pasadena is a census-designated place in Anne Arundel County, Maryland, United States. The population was 24,287 at the 2010 census. The areas of Lake Shore, Riviera Beach and Pasadena are collectively referred to as Pasadena by residents. As all areas are governed by Anne Arundel County, there is no distinction in services such as fire, police…Pasadena is a census-designated place in Anne Arundel County, Maryland, United States. The population was 24,287 at the 2010 census. The areas of Lake Shore, Riviera Beach and Pasadena are collectively referred to as Pasadena by residents. As all areas are governed by Anne Arundel County, there is no distinction in services such as fire, police, or public schools. All three areas are encompassed by the 21122 zip code. The collective area population was at 56,441 at the 2010 census.