Twin cities are a special case of two neighboring cities or urban centres that grow into a single conurbation – or narrowly separated urban areas – over time. There are no formal criteria, but twin cities are generally comparable in status and size, though not necessarily equal; a city and a substantially smaller suburb would not typically qualify, even if they were once separate. Tri-cities and quad cities are similar phenomena involving three or four municipalities.
33-643: Lewiston–Auburn ( L–A ) are twin cities in Androscoggin County, Maine , USA. Together, they have a population of 61,182 in a combined 101 square miles (260 km). The cities are commonly called "Cities of the Androscoggin," as they are seated along the banks of the Androscoggin River which separates them. They share infrastructure and transportation, such as the Lewiston-Auburn CityLink ,
66-489: A location identifier , is a three-letter geocode designating many airports and metropolitan areas around the world, defined by the International Air Transport Association (IATA). The characters prominently displayed on baggage tags attached at airport check-in desks are an example of a way these codes are used. The assignment of these codes is governed by IATA Resolution 763, and it
99-550: A new airport is built, replacing the old one, leaving the city's new "major" airport (or the only remaining airport) code to no longer correspond with the city's name. The original airport in Nashville, Tennessee, was built in 1936 as part of the Works Progress Administration and called Berry Field with the designation, BNA. A new facility known as Nashville International Airport was built in 1987 but still uses BNA. This
132-508: A very large percentage of citizens who identify as so. In the 2000 census, 19.4% of those five and older in the cities combined (more so on the Lewiston side of the river) said that they spoke French. Auburn was incorporated in 1842, and has a population of 24,061. Lewiston was incorporated in 1863, and has a population of 37,121. For years, the idea of consolidating the cities into one has floated around. Proponents have cited budget savings and
165-499: Is GSN and its IATA code is SPN, and some coincide with IATA codes of non-U.S. airports. Canada's unusual codes—which bear little to no similarity with any conventional abbreviation to the city's name—such as YUL in Montréal , and YYZ in Toronto , originated from the two-letter codes used to identify weather reporting stations in the 1930s. The letters preceding the two-letter code follow
198-606: Is administered by the IATA's headquarters in Montreal , Canada. The codes are published semi-annually in the IATA Airline Coding Directory. IATA provides codes for airport handling entities, and for certain railway stations. Alphabetical lists of airports sorted by IATA code are available. A list of railway station codes , shared in agreements between airlines and rail lines such as Amtrak , SNCF , and Deutsche Bahn ,
231-600: Is available. However, many railway administrations have their own list of codes for their stations, such as the list of Amtrak station codes . Airport codes arose out of the convenience that the practice brought pilots for location identification in the 1930s. Initially, pilots in the United States used the two-letter code from the National Weather Service (NWS) for identifying cities. This system became unmanageable for cities and towns without an NWS identifier, and
264-518: Is different from the name in English, yet the airport code represents only the English name. Examples include: Due to scarcity of codes, some airports are given codes with letters not found in their names: The use of 'X' as a filler letter is a practice to create three-letter identifiers when more straightforward options were unavailable: Some airports in the United States retained their NWS ( National Weather Service ) codes and simply appended an X at
297-513: Is in conjunction to rules aimed to avoid confusion that seem to apply in the United States, which state that "the first and second letters or second and third letters of an identifier may not be duplicated with less than 200 nautical miles separation." Thus, Washington, D.C. area's three airports all have radically different codes: IAD for Washington–Dulles , DCA for Washington–Reagan (District of Columbia Airport), and BWI for Baltimore (Baltimore–Washington International, formerly BAL). Since HOU
330-532: Is not followed outside the United States: In addition, since three letter codes starting with Q are widely used in radio communication, cities whose name begins with "Q" also had to find alternate codes, as in the case of: IATA codes should not be confused with the FAA identifiers of U.S. airports. Most FAA identifiers agree with the corresponding IATA codes, but some do not, such as Saipan , whose FAA identifier
363-416: Is used for William P. Hobby Airport , the new Houston–Intercontinental became IAH. The code BKK was originally assigned to Bangkok–Don Mueang and was later transferred to Suvarnabhumi Airport , while the former adopted DMK. The code ISK was originally assigned to Gandhinagar Airport (Nashik's old airport) and later on transferred to Ozar Airport (Nashik's current airport). Shanghai–Hongqiao retained
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#1732852602857396-561: The Canadian transcontinental railroads were built, each station was assigned its own two-letter Morse code : When the Canadian government established airports, it used the existing railway codes for them as well. If the airport had a weather station, authorities added a "Y" to the front of the code, meaning "Yes" to indicate it had a weather station or some other letter to indicate it did not. When international codes were created in cooperation with
429-707: The Lewiston and Auburn Railroad Company and the Auburn/Lewiston Municipal Airport . They also form the Lewiston-Auburn Metropolitan Statistical Area , which encompasses Androscoggin County. The Lewiston–Auburn Economic Growth Council has been promoting the cities as one community for decades in its campaign to promote growth in industry and business. The twin cities have a long history of French-Canadian immigration, and still retain
462-687: The Mississippi River , and competed for prominence as they grew. In some cases, twin cities are separated by a state border, such as Albury ( New South Wales ) and Wodonga ( Victoria ) in Australia, on opposite sides of the Murray River . In Pakistan , Islamabad and Rawalpindi are twin cities located in northwestern Punjab region with Islamabad, administratively being part of the Islamabad Capital Territory , and Rawalpindi, part of
495-510: The province of Punjab . Cities on opposite sides of international borders sometimes share enough cultural and historical identity to be seen as twins, such as Haparanda ( Sweden ) and Tornio ( Finland ), Leticia ( Colombia ) and Tabatinga ( Brazil ), or Valga ( Estonia ) and Valka ( Latvia ). In some cases twin cities eventually merge into a single legal municipality, such as Buda and Pest merging in 1873 into Budapest , Hungary; Brooklyn being annexed by New York City in 1898; or
528-481: The United States, because "Y" was seldom used in the United States, Canada simply used the weather station codes for its airports, changing the "Y" to a "Z" if it conflicted with an airport code already in use. The result is that most major Canadian airport codes start with "Y" followed by two letters in the city's name (for example, YOW for O tta w a , YWG for W innipe g , YYC for C algar y , or YVR for V ancouve r ), whereas other Canadian airports append
561-440: The airport itself instead of the city it serves, while another code is reserved which refers to the city itself which can be used to search for flights to any of its airports. For instance: Or using a code for the city in one of the major airports and then assigning another code to another airport: When different cities with the same name each have an airport, they need to be assigned different codes. Examples include: Sometimes,
594-418: The airport's former name, such as Orlando International Airport 's MCO (for Mc C o y Air Force Base), or Chicago's O'Hare International Airport , which is coded ORD for its original name: Or char d Field. In rare cases, the code comes from the airport's unofficial name, such as Kahului Airport 's OGG (for local aviation pioneer Jimmy H ogg ). In large metropolitan areas, airport codes are often named after
627-439: The already existing sense of community and unity that exists. In May 2013, city councilors from both cities discussed the possibility of merging through a new voter-approved charter. With most in support, they agreed to discuss further in detail at a later point. In 2017, a vote on merging the two cities appeared on city ballots. The measure was rejected by a wide margin, with 84% of Auburn voters and 66% of Lewiston voters rejected
660-491: The code SHA, while the newer Shanghai–Pudong adopted PVG. The opposite was true for Berlin : the airport Berlin–Tegel used the code TXL, while its smaller counterpart Berlin–Schönefeld used SXF; the Berlin Brandenburg Airport has the airport code BER, which is also part of its branding. The airports of Hamburg (HAM) and Hannover (HAJ) are less than 100 nautical miles (190 km) apart and therefore share
693-919: The end. Examples include: A lot of minor airfields without scheduled passenger traffic have ICAO codes but not IATA codes, since the four letter codes allow more number of codes, and IATA codes are mainly used for passenger services such as tickets, and ICAO codes by pilots. In the US, such airfields use FAA codes instead of ICAO. There are airports with scheduled service for which there are ICAO codes but not IATA codes, such as Nkhotakota Airport/Tangole Airport in Malawi or Chōfu Airport in Tokyo, Japan. There are also several minor airports in Russia (e.g., Omsukchan Airport ) which lack IATA codes and instead use internal Russian codes for booking. Flights to these airports cannot be booked through
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#1732852602857726-557: The first three letters of the city in which it is located, for instance: The code may also be a combination of the letters in its name, such as: Sometimes the airport code reflects pronunciation, rather than spelling, namely: For many reasons, some airport codes do not fit the normal scheme described above. Some airports, for example, cross several municipalities or regions, and therefore, use codes derived from some of their letters, resulting in: Other airports—particularly those serving cities with multiple airports—have codes derived from
759-474: The following format: Most large airports in Canada have codes that begin with the letter "Y", although not all "Y" codes are Canadian (for example, YUM for Yuma, Arizona , and YNT for Yantai , China), and not all Canadian airports start with the letter "Y" (for example, ZBF for Bathurst, New Brunswick ). Many Canadian airports have a code that starts with W, X or Z, but none of these are major airports. When
792-593: The form of " YYZ ", a song by the rock band Rush , which utilizes the Morse code signal as a musical motif. Some airports have started using their IATA codes as brand names , such as Calgary International Airport (YYC) and Vancouver International Airport (YVR). Numerous New Zealand airports use codes that contain the letter Z, to distinguish them from similar airport names in other countries. Examples include HLZ for Hamilton , ZQN for Queenstown , and WSZ for Westport . Predominantly, airport codes are named after
825-482: The international air booking systems or have international luggage transferred there, and thus, they are booked instead through the airline or a domestic booking system. Several heliports in Greenland have 3-letter codes used internally which might be IATA codes for airports in faraway countries. There are several airports with scheduled service that have not been assigned ICAO codes that do have IATA codes, especially in
858-515: The merger. This Maine state location article is a stub . You can help Misplaced Pages by expanding it . Twin cities A common – but not universal – scenario is two cities that developed concurrently on opposite sides of a river. For example, Minneapolis and Saint Paul in Minnesota – one of the most widely known pairs of "Twin Cities" – were founded several miles apart on opposite sides of
891-612: The name of the airport itself, for instance: This is also true with some cities with a single airport (even if there is more than one airport in the metropolitan area of said city), such as BDL for Hartford, Connecticut 's B ra dl ey International Airport or Baltimore's BWI, for B altimore/ W ashington I nternational Airport ; however, the latter also serves Washington, D.C. , alongside Dulles International Airport (IAD, for I nternational A irport D ulles) and Ronald Reagan Washington National Airport (DCA, for D istrict of C olumbia A irport). The code also sometimes comes from
924-416: The one they are located in: Other airport codes are of obscure origin, and each has its own peculiarities: In Asia, codes that do not correspond with their city's names include Niigata 's KIJ , Nanchang 's KHN and Pyongyang 's FNJ . EuroAirport Basel Mulhouse Freiburg , which serves three countries, has three airport codes: BSL, MLH, EAP. Some cities have a name in their respective language which
957-501: The same first and middle letters, indicating that this rule might be followed only in Germany. Many cities retain historical names in their airport codes, even after having undergone an official name/spelling/transliteration change: Some airport codes are based on previous names associated with a present airport, often with a military heritage. These include: Some airports are named for an administrative division or nearby city, rather than
990-497: The station code of Malton, Mississauga , where it is located). YUL is used for Montréal–Trudeau (UL was the ID code for the beacon in the city of Kirkland , now the location of Montréal–Trudeau). While these codes make it difficult for the public to associate them with a particular Canadian city, some codes have become popular in usage despite their cryptic nature, particularly at the largest airports. Toronto's code has entered pop culture in
1023-498: The three ancient cities of Hankou , Hanyang , and Wuchang joining in 1927 into Wuhan . As a single urban area, twin cities may share an airport whose airport codes include both cities' initials, e.g., DFW ( Dallas–Fort Worth ), LBA ( Leeds – Bradford ), MSP ( Minneapolis–Saint Paul ), RDU ( Raleigh and Durham ), and CAK ( Akron – Canton ). IATA airport code An IATA airport code , also known as an IATA location identifier , IATA station code , or simply
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1056-504: The two-letter code of the radio beacons that were the closest to the actual airport, such as YQX in Gander or YXS in Prince George . Four of the ten provincial capital airports in Canada have ended up with codes beginning with YY, including: Canada's largest airport is YYZ for Toronto Pearson (as YTZ was already allocated to Billy Bishop Toronto City Airport , the airport was given
1089-529: The use of two letters allowed only a few hundred combinations; a three-letter system of airport codes was implemented. This system allowed for 17,576 permutations, assuming all letters can be used in conjunction with each other. Since the U.S. Navy reserved "N" codes, and to prevent confusion with Federal Communications Commission broadcast call signs , which begin with "W" or "K", the airports of certain U.S. cities whose name begins with one of these letters had to adopt "irregular" airport codes: This practice
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