Double placenames prominently feature the placenames of two or more constituents in double-barrelled form rather than invent a new name. This is often out of consideration for local sensitivities, since the smaller entity may resent its takeover, and may demand its symbolic perpetuation within an amalgamated name so as to propagate the impression of a merger between equals.
Styles In their English forms, the conjoined names may have the following patterns: concatenation, e.g. Papua New Guinea grammatical conjunction, e.g. Trinidad and Tobago
The punctuation and capitalization practices in written English vary: merging into one word without an intermediate space, e.g. Budapest standing apart, e.g. Papua New Guinea conjunction by hyphenation. While English-speakers are relaxed about using a hyphen or not, this punctuation once caused controversy between Czechs and Slovaks conjunction with an en dash, typically when the usage is associative, attributive or is a juxtaposition of two independent entities. CamelCase may sometimes be attempted, but many style guides recommend against this in formal English-language use.
Three-word names for two-part entities are often ambiguous. For example, it may not be clear whether North Rhine-Westphalia is an amalgamation between the north part of the Rhine Province on the one hand and Westphalia on the other (true) or the northern division of some pre-existing place called Rhine-Westphalia (false). While this problem does not arise in German, no entirely satisfactory punctuation of such names has been established in English. In the above case, the hyphen is often omitted because it is misleading. It has been proposed that this state's name be punctuated "North-Rhine/Westphalia" in English, but the solidus or forward slash is also ambiguous.
Neologisms Some names have been merged and modified as an alternative to using hyphenation or grammatical conjunction: BosWash: the megalopolis extending from Boston to Washington, D.C., CamelCase example (extended in fiction into a Boston–Atlanta Metropolitan Axis or BAMA covering most of the US East Coast) SeaTac: another example of CamelCase (Seattle and Tacoma, Washington) Czechoslovakia: the Czech lands and Slovakia Senegambia: Senegal and Gambia Tanzania: Tanganyika and Zanzibar
False double placenames Binomial placenames are not true double placenames, but elements in a hierarchical naming system. They are a means of distinguishing two entities which share a parent geographic feature. Examples: Guinea-Bissau (official name of the country with capital Bissau, as distinct from Guinea, with capital Conakry) Congo-Brazzaville and Congo-Kinshasa (from the respective capitals of what are officially Republic of the Congo and Democratic Republic of the Congo)
They are often used for railway stations and airports: King's Cross St Pancras, the London Underground station serving two separate London railway terminals: King's Cross and St Pancras railway stations. Paris - Orly Airport, one of two Paris airports Trenton–Mercer Airport, actually located in Ewing, outside Trenton, both in Mercer County. Trenton–Mercer is an example of a marketing decision in which a small airport tries to associate itself with a larger city. Ryanair has been criticized for promoting names for airports unusually far from the city from which they are named, such as Paris Beauvais Tillé Airport (a triple name) and Frankfurt-Hahn Airport.
Binomial names may be seen in German-language texts to denominate parts of towns: Bergen-Belsen: the Belsen section within the municipality of Bergen. (This form is now fixed in English when referring to the Nazi concentration camp and the present memorial there.) Berlin-Charlottenburg: the district of Charlottenburg, Berlin
The word "and" in its name does not always signify the union of two distinct territories: Sala y Gómez: one island named for two people Lewis and Clark County, Montana: named for Meriwether Lewis and William Clark
In dual naming, words in two different languages have been joined by a hyphen or a slash to become the community's (or geographic feature's) official name, often because of language politics: Vitoria-Gasteiz: the combination of this city's Spanish name of Vitoria and Basque name of Gasteiz Dingle/Daingean Uí Chúis: proposed official name (combining English and Irish-language names) of a town in the County Kerry Gaeltacht. Aoraki / Mount Cook: mountain in New Zealand with Māori and English names combined. Many geographic features of New Zealand are officially designated in a similar way (and the country as a whole is sometimes unofficially referred to as "Aotearoa New Zealand").
Similarly, places may simply have an official name which consists of two names, such as the Australian territory of the Cocos (Keeling) Islands, which consists of the North Keeling Island and the South Keeling Islands.
Transitional names Sometimes names will be concatenated during a name change. Zimbabwe Rhodesia was the name of the former Rhodesia and future Zimbabwe from June 1 to December 12, 1979.
Sovereign states Antigua and Barbuda: Antigua and Barbuda Bosnia and Herzegovina: Bosnia and Herzegovina Papua New Guinea: Territories of Papua and New Guinea; Papua and New Guinea are actually alternate names of the same island, New Guinea, but have been used officially for different parts of this island São Tomé and Príncipe: São Tomé and Príncipe Saint Kitts and Nevis: Saint Kitts and Nevis Saint Vincent and the Grenadines: Saint Vincent and Grenadines Trinidad and Tobago: Trinidad and Tobago United Kingdom of Great Britain and Northern Ireland: Great Britain and Northern Ireland
Non-sovereign entities
Dependent territories Andaman and Nicobar Islands: Andaman Islands and Nicobar Islands (India) Dadra and Nagar Haveli and Daman and Diu (India): Daman and Diu (Daman and Diu) and Dadra and Nagar Haveli (Dadra and Nagar Haveli) Ashmore and Cartier Islands: Ashmore Island and Cartier Island (Australia) Heard Island and McDonald Islands: Heard Island and McDonald Island (Australia) Saint Pierre and Miquelon: Saint Pierre Island and Miquelon (France) South Georgia and the South Sandwich Islands: South Georgia and South Sandwich Islands (United Kingdom) Sovereign Base Areas of Akrotiri and Dhekelia: Akrotiri and Dhekelia Cantonment (United Kingdom) Trindade and Martim Vaz: Trindade Island and Martim Vaz Island (Brazil) Saint Peter and Saint Paul: Saint Peter island and Saint Paul Island (Brazil) Turks and Caicos Islands: Turks and Caicos (United Kingdom) Wallis and Futuna Islands: Wallis Island and Futuna Islands (France)
Regions of states Arica y Parinacota Region: Arica and Parinacota (Chile) Emilia-Romagna: Emilia and Romagna (Italy) Friuli-Venezia Giulia: Friuli and Venezia Giulia (Italy) Trás-os-Montes e Alto Douro: Trás-os-Montes and Alto Douro (Portugal) Trentino-Alto Adige/Südtirol: Trentino and South Tyrol, formerly Alto Adige (Italy)
States of federations Baden-Württemberg: Baden and Württemberg (Germany) Mecklenburg-Vorpommern: Mecklenburg and Vorpommern (Germany) Newfoundland and Labrador: Newfoundland and Labrador (Canada) North Rhine-Westphalia: part of the Rhineland with Westphalia (Germany) Rhineland-Palatinate: part of the Rhineland with the Palatinate (Germany) Rhode Island and Providence Plantations: Rhode Island proper and Providence Plantations (United States) The name of the state was officially shortened to "Rhode Island" in 2020. Saxony-Anhalt: part of Saxony with Anhalt (Germany) Schleswig-Holstein: Schleswig and Holstein (Germany)
Four regions of France, several federal subjects of Russia, most local government districts of Northern Ireland and some autonomous communities of Spain (Castile and León, Castile-La Mancha) also feature two or more placenames conjoined by a hyphen or with the word "and" (or its translation).
Provinces and counties Aetolia-Acarnania: Aetolia and Acarnania (Greece) Bà Rịa–Vũng Tàu province (Vietnam) Gothenburg and Bohus (historic): Gothenburg and Bohuslän (Sweden) Kuyavian-Pomeranian Voivodeship: Kuyavia and Pomerania (Poland) Møre og Romsdal: Møre and Romsdal (Norway) Newfoundland and Labrador (Canada) Ross and Cromarty (historic): Ross-shire and Cromartyshire (Scotland) Sogn og Fjordane (historic): Sogn and the fjords (Norway) Thừa Thiên–Huế Province (Vietnam) Warmian-Masurian Voivodeship: Warmia and Masuria (Poland)
Capital cities Budapest formed in 1873 by the amalgamation of three former capitals, Buda and Óbuda (Old Buda) on the right bank of the Danube, and Pest on the left bank.
Other cities and towns Bielsko-Biała, a Polish city, is composed of two former towns on opposite banks of the Biała River, Silesian Bielsko and Lesser Poland's Biała, merged in 1951, both deriving from "white" (biała) in Polish. Boguszów-Gorce, Polish town composed of two former towns of Boguszów and Gorce, merged in 1973 Boldești-Scăeni, Romanian town composed of two former settlements of Boldești and Scăeni, merged in 1968 Boulogne-Billancourt is the name of an industrial in the western suburbs of Paris, France. In 1924, the commune Boulogne-sur-Seine was officially renamed Boulogne-Billancourt to reflect the development of the industrial neighbourhood of Billancourt annexed in 1860. Many smaller French communes have been forced to merge, and double-barrelled names referring to two separate villages are not uncommon (e.g. Boutigny-Prouais in Eure-et-Loir). Corigliano-Rossano, Italian comune composed of two former towns of Corigliano Calabro and Rossano, merged in 2018 Czechowice-Dziedzice, Polish town composed of two former settlements of Czechowice and Dziedzice, merged in 1951, under current name since 1958 Czerwionka-Leszczyny, Polish town composed of two former towns of Czerwionka and Leszczyny, merged in 1962 Dallas–Fort Worth is a metroplex and the usual name for the Dallas–Fort Worth–Arlington metropolitan area in Texas. Golub-Dobrzyń, Polish town composed of two former towns of Golub and Dobrzyń on opposite banks of the Drwęca River, merged in 1951 Jelcz-Laskowice, Polish town composed of two former municipalities of Jelcz and Laskowice Oławskie, merged in 1987 Kędzierzyn-Koźle, Polish city composed of two former towns of Kędzierzyn and Koźle, merged in 1975 Knokke-Heist is a municipality located in the Belgian province of West Flanders. The municipality comprises the towns Knokke and Heist-aan-Zee that merged also with some other minor locations in 1971. Konstancin-Jeziorna, Polish town composed of two former towns of Skolimów-Konstancin and Jeziorna, merged in 1969 Mänttä-Vilppula, Finnish town composed of two former municipalities of Mänttä and Vilppula, merged in 2009 Morkovice-Slížany, Czech town composed of two former municipalities of Morkovice and Slížany, merged in 1960 Popești-Leordeni, Romanian town composed of two former settlements of Popești and Leordeni, merged in 1873 Rájec-Jestřebí, Czech town composed of two former municipalities of Rájec and Jestřebí, merged in 1960 Ruciane-Nida, Polish town composed of two former settlements of Ruciane and Nida, merged in 1966 Šaštín-Stráže, Slovak town composed of two former settlements of Šaštín and Stráže, merged in 1961 Sedlec-Prčice, Czech town composed of two former municipalities of Sedlec and Prčice, merged in 1957 Tel Aviv-Yafo, located on the Israeli coastal plain, was formed in 1950 when the ancient port city of Jaffa was merged with the Tel Aviv municipality to its north.
Former place names Includes defunct personal unions and dissolved political unions. Abruzzi e Molise: Abruzzo and Molise Araucania and Patagonia: Araucanía and Patagonia Austria-Hungary: Austria and Hungary Bithynia et Pontus: Bithynia and Pontus Corsica et Sardinia: Corsica and Sardinia Croatia-Slavonia: Croatia and Slavonia Denmark–Norway: Denmark and Norway Gilbert and Ellice Islands: Gilbert Islands and Ellice Islands Gorizia and Gradisca: Gorizia and Gradisca