Class B is a class of airspace in the United States which follows International Civil Aviation Organization (ICAO) airspace designation. Class B airspace areas are designed to improve aviation safety by reducing the risk of midair collisions in the airspace surrounding airports with high-density air traffic operations. Aircraft operating in these airspace areas are subject to certain operating rules and equipment requirements. Class B airspace protects the approach and departure paths from aircraft not under air traffic control. All aircraft inside Class B airspace are subject to air traffic control. Traffic operating under VFR must be identified on radar and explicitly cleared into the airspace before they can enter. The airspace is commonly depicted as resembling an "upside-down wedding cake". The innermost ring extends from the surface area around the airport to typically 10,000' MSL. Several outer rings usually surround it with progressively higher floors to allow traffic into nearby airports without entering the primary airport's Class B airspace. The airspace around the busiest US airports is classified as ICAO Class B, and the primary airport (one or more) for which this airspace is designated is called Class B airport. As of January 2023, there are 37 Class B airports in the United States. Despite common misconception, Nellis Air Force Base and Dallas Love Field Airport are not designated as Class B airports; however, in both cases the Class B airspace for the primary airport in the region (Harry Reid International and Dallas/Fort Worth International, respectively) has been specifically extended to cover these airports as if they were themselves Class B. The following list of Class B airports is sorted by state and IATA Airport Code/ICAO Airport Code. Arizona: PHX / KPHX Phoenix Sky Harbor International California: LAX / KLAX Los Angeles International NKX / KNKX Marine Corps Air Station Miramar SAN / KSAN San Diego International/Lindbergh Field SFO / KSFO San Francisco International Colorado: DEN / KDEN Denver International Florida: MCO / KMCO Orlando International MIA / KMIA Miami International TPA / KTPA Tampa International Georgia: ATL / KATL Hartsfield–Jackson Atlanta International Hawaii: HNL / PHNL Honolulu International Illinois: ORD / KORD Chicago–O'Hare International Kentucky: CVG / KCVG Cincinnati/Northern Kentucky International Louisiana: MSY / KMSY Louis Armstrong New Orleans International Maryland: ADW / KADW Andrews Air Force Base BWI / KBWI Baltimore/Washington International Massachusetts: BOS / KBOS Boston–Logan International Michigan: DTW / KDTW Detroit Metropolitan Wayne County Minnesota: MSP