The University of Florida (commonly referred to as Florida, UF or U of F) is an American public land-grant, sea-grant, and space-grant research university located on a 2,000-acre (8.1 km) campus in Gainesville, Florida. The university traces its historical origins to 1853, and has operated continuously on its present Gainesville campus since September 1906. It has been included among the so-called "Public Ivy" universities—one of the top public universities in the United States. The University of Florida is currently ranked fifty-third overall among all national universities, public and private, in the current 2011 U.S. News & World Report rankings and consistently ranks within the top 100 universities worldwide. The University of Florida is an elected member of the Association of American Universities (AAU), an organization composed of sixty-one American and Canadian research universities. It is one of three "research flagship universities" within the State University System of Florida, as designated by the Florida Legislature.