Rio Grande is an unincorporated community and census-designated place (CDP) located within Middle Township and Lower Township in Cape May County, in the U.S. state of New Jersey.

Middle Township is a township in Cape May County, in the U.S. state of New Jersey. The township, and all of Cape May County, is part of the Ocean City metropolitan statistical area, and is part of the Philadelphia-Wilmington-Camden, PA-NJ-DE-MD combined statistical area, also known as the Delaware Valley or Philadelphia metropolitan area. As of the 2020 United States census, the township's population was 20,380, an increase of 1,469 (+7.8%) from the 2010 census count of 18,911, which in turn reflected an increase of 2,506 (+15.3%) from the 16,405 counted in the 2000 census. The township's Cape May Court House section is the county seat of Cape May County.