Question: Which is the busiest airport in the United Kingdom outside of London?

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Boise Airport (IATA: BOI, ICAO: KBOI, FAA LID: BOI) (Boise Air Terminal or Gowen Field) is a joint civil-military airport three miles south of Boise in Ada County, Idaho, United States.  The airport is operated by the city of Boise Department of Aviation and is overseen by an Airport Commission.  It is by far the busiest airport in the state of Idaho, serving more passengers than all other Idaho airports combined and roughly ten times as many passengers as Idaho's second busiest airport, Idaho Falls Regional Airport. Grantley Adams International Airport (GAIA) (IATA: BGI, ICAO: TBPB) is the international airport of Barbados, located in Seawell, Christ Church.  It is the only designated port of entry for persons arriving and departing by air in Barbados and operates as a major gateway to the Eastern Caribbean.  The airport has direct service to destinations in the United States, Canada, Central America and Europe and serves as the second hub for LIAT.  In 2016, the airport was the 8th busiest airport in the Caribbean region; and the third busiest airport in the Lesser Antilles; after Queen Beatrix International Airport located in Aruba, and Pointe-à-Pitre International Airport located in the Republic of France within the island of Guadeloupe.  GAIA, also remains an important air-link for cruise ship passengers departing and arriving at the Port of Bridgetown, and a base of operations for the Regional Security System (RSS), and the Regional (Caribbean) Police Training Centre. The world's busiest airports by passenger traffic are measured by total passengers (data from Airports Council International), defined as passengers enplaned plus passengers deplaned plus direct-transit passengers.  Hartsfield–Jackson Atlanta International Airport has been the world's busiest airport every year since 2000; with all airports combined London has the world's busiest city airport system by passenger count.  As of 2016, seven countries have at least two airports in the top 50; the United States of America has 16, China has 8 (including Hong Kong), and the United Kingdom, Japan, Germany, India and Spain have two airports each. International air travel from the United Kingdom refers to the commercial carriage of passengers between the UK and the rest of the world.  In 2008, London Heathrow Airport which is also the busiest international airport on Earth handled 67,054,745 passengers which is more than the total population of the United Kingdom.  The 20 busiest airports in the UK handled close to 230 million passengers in 2008 (185 million of whom were international passengers).  The geographical size of the UK means that many flights that would be considered domestic in for example the United States are actually international (i.e. the distance from Heathrow to Charles de Gaulle Airport is roughly the same as the distance between John F. Kennedy International Airport and Washington Dulles International Airport).  The London airports, Heathrow, Gatwick and Stansted alongside Manchester Airport rank amongst the world's busiest airports by international passenger traffic.  According to 2008 statistics the best served nations by direct flights from the UK were France, Italy, Spain, the United States and Germany with 50, 34, 33, 31 and 29 respectively.  Overall Spain was the nation that saw the most passengers arrive from the UK in 2008, with a total of 34,557,729 (almost double the number that flew to the United States) John F. Kennedy International Airport (IATA: JFK, ICAO: KJFK, FAA LID: JFK) , often referred to as Kennedy Airport, or simply JFK, is the primary international airport serving New York City.  It is the busiest international air passenger gateway into North America, the fifth busiest airport in the United States and the busiest airport in the New York City airport system, handling just under 59 million passengers in 2016.  Over ninety airlines operate out of the airport, with non-stop or direct flights to destinations in all six inhabited continents. Rochester International Airport (IATA: RST, ICAO: KRST, FAA LID: RST) is a nonhub primary airport located seven miles (11 km) southwest of the central business district of Rochester, a city in Olmsted County, Minnesota, United States.  It is the second busiest airport in Minnesota, however it is the third busiest airport for commercial airlines in Minnesota, behind Duluth International Airport .  It used to be called "Rochester Municipal Airport", which was its name before adding customs and immigration facilities specifically for Mayo Clinic purposes in 1995. Dubai International Airport (IATA: DXB, ICAO: OMDB) (Arabic: مطار دبي الدولي‎ ‎ ) is the primary international airport serving Dubai, United Arab Emirates and is the world's busiest airport by international passenger traffic.  It is also the 3rd busiest airport in the world by passenger traffic, the 6th busiest cargo airport in world, the busiest airport for Airbus A380 and Boeing 777 movements, and the busiest airport in the world operating with only two runways.  In 2016, DXB handled 83.6 million passengers, 2.59 million tonnes of cargo and registered 418,220 aircraft movements. Hartsfield–Jackson Atlanta International Airport (IATA: ATL, ICAO: KATL, FAA LID: ATL) , also known as Atlanta Airport, Hartsfield, or Hartsfield–Jackson, is an international airport located 7 mi south of Atlanta's central business district, in the U.S. state of Georgia.  It has been the world's busiest airport by passenger traffic since 1998; and by number of landings and take-offs from 2005 to 2013, losing that title to Chicago-O'Hare in 2014, but regaining it a year later.  Hartsfield–Jackson held its ranking as the world's busiest airport in 2012, both in passengers and number of flights, by accommodating 100 million passengers (more than 260,000 passengers daily) and 950,119 flights.  Many of the nearly one million flights are domestic flights from within the United States, where the airport serves as a major hub for travel throughout the southeastern region of the country.  The airport has 207 domestic and international gates.  ATL covers 4,700 acres (1,902 ha) of land. Heathrow Airport (also known as London Heathrow) (IATA: LHR, ICAO: EGLL) is a major international airport in London, United Kingdom.  Heathrow is the second busiest airport in the world by international passenger traffic (surpassed by Dubai International in 2014), as well as the busiest airport in Europe by passenger traffic, and the seventh busiest airport in the world by total passenger traffic.  In 2016, it handled a record 75.7 million passengers, a 1.0% increase from 2015. Gatwick Airport (also known as London Gatwick) (IATA: LGW, ICAO: EGKK) is a major international airport in south-east England, 29.5 mi south of Central London and 2.7 NM north of Crawley.  It is the second-busiest airport by total passenger traffic in the United Kingdom, after London Heathrow.  Gatwick is the eighth-busiest airport in Europe.  Until 2016, it was the busiest single-use runway airport in the world before being overtaken by Mumbai's Chhatrapati Shivaji International Airport.

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Gatwick Airport (also known as London Gatwick) (IATA: LGW, ICAO: EGKK) is a major international airport in south-east England, 29.5 mi south of Central London and 2.7 NM north of Crawley.  It is the second-busiest airport by total passenger traffic in the United Kingdom, after London Heathrow. Heathrow Airport (also known as London Heathrow) (IATA: LHR, ICAO: EGLL) is a major international airport in London, United Kingdom.