2000s, in 2004, the airport became an official US port of entry and achieved international status. To reflect the change, it was renamed again, becoming the Chicago/Rockford International Airport (the slash was removed in 2007), bringing it in line with the two "Chicago" airports (O'Hare and Midway). In many forms of media, the airport also markets itself by its three FAA/IATA call letters: RFD. Today the Rockford airport is marketed to residents of Rockford and surrounding areas as an alternative to Chicago Midway International Airport and O'Hare International Airport in Chicago, Mitchell International Airport in Milwaukee and Dane County Regional Airport in Madison, Wisconsin, as well as limited service airports such as Dubuque Regional Airport in Iowa. The airlines at Rockford often use their low fares as a selling point. Allegiant Air began service between Rockford and Las Vegas in November 2005 and between Rockford and St. Petersburg-Clearwater in September 2006. Bell Bowl Prairie Bell Bowl Prairie is a remnant gravel hill prairie located in within the confines of Rockford Airport. It is considered a Category I Illinois Natural Areas Inventory site due to its high quality natural community of native flora and fauna. Assessed in 2018, 5 acres of the approximately 22-acre prairie were considered high quality (roughly corresponding to the INAI area), and 4.2 acres were considered "moderate quality". In 2021, most of the prairie is planned to be demolished as part of the Chicago Rockford International Airport's expansion plans. Rockford AirFest The Rockford airport has played host to airshows in several capacities, often becoming one of the largest events in Northern Illinois. In 1959 the Experimental Aircraft Association (EAA) moved its annual fly-in from Timmerman Field in Milwaukee to the Greater Rockford Airport after outgrowing the smaller Wisconsin airfield. In 1960, 1000 people attended, leading to growth each year through the 1960s. 1969 would be the final year for the EAA fly-in in Rockford, as it had outgrown the Rockford airport. For 1970, the EAA would move its annual convention/fly-in to Wittman Regional Airport in Oshkosh, Wisconsin, where it has been held ever since. In 1986 the Greater Rockford Airport returned to hosting large-scale air shows with the Midwest AirFest. From 1986 to 1994, the show would twice feature the United States Air Force Thunderbirds. After an 11-year hiatus, the AirFest (rebranded as the Rockford AirFest) returned in 2005. The airshow is one of the few in