Twin towns

Twin towns may refer to one of:
 * Town twinning, two geographically-disparate municipalities which have been paired as twin towns, partner cities or sister cities as part of a cultural, economic or paradiplomatic exchange.
 * Twin cities, two adjacent but distinct municipalities - often on opposite banks of the same river or opposite sides of a border.

Town twinning
There are thousands of "twinned town", "partner city" or "sister city" pairs. Many amount to little more than an official municipal proclamation, a plaque at the town hall, a flag raising or a "Welcome to X, twinned with Y and Z" sign at the city limits. Occasionally the city will send a small group on a trip or junket as part of an economic or cultural exchange; often, the task of maintaining the relationship will be passed to a small, non-profit local group.

Most of these efforts have limited or no impact for the average visitor to the city; at best a small student group may be sent abroad occasionally on a cultural exchange, at worst the twin link is proclaimed, posted and promptly forgotten.

Exceptionally, visitors may encounter public artwork or monuments referencing a town twinning; in a few instances, the public is invited to an annual local event with a theme referencing the foreign city or nation.

See

 * A sister cities bridge, often a footbridge across a small stream with space to fly national flags of international siblings, commemorates twinning relationships to cities including Kansas City (Missouri), Rochester (New York) and Rockville (Maryland).
 * Artwork or public sculpture sometimes recognises a twinned municipality. Baltimore (Maryland) proudly displays a Stone Lantern on a pedestal at the Inner Harbour, a gift from its Japanese sibling Kawasaki. Rome displays a column in honour of its exclusive twinning to Paris. Seattle displays a bell on its 1962 World's Fair site (Seattle Center) to represent its twinning with Kobe.
 * A local park, such as Kobe Terrace or Tashkent Park in Seattle, may be named for a twinned sibling. Displays of international flags or directional signage with the distance to each twin are also common.
 * A group of street names may reflect sibling relationships, such as Cebu City's Sister Cities Drive plus individual roads for each sibling: Kaohsiung Street (for Kaohsiung, Taiwan), Salinas Drive (for Salinas, California) and Belgium Street (for Kortrijk, Belgium).
 * Signs or markers, often indicating the distance to some or all of the twin towns, Erlangen for example has a piece of sandstone donated by sister town Jena in front of city hall which lists all twin towns and their distance from Erlangen.

Do

 * Boring & Dull Day. Boring, Oregon. Aug. 9, annual celebration of sibling relationship with Dull, Scotland.
 * Bastille Day Block Party, Larchmont, NY. July 14, annual celebration of sibling relationship between La Rochelle, France and New Rochelle, New York.
 * A local group in Toledo (Ohio) hosts a one-day international festival at the University of Toledo in mid-April in honour of the city's long-standing partnership with namesake Toledo (Spain).

Connect

 * Romeo (Michigan) and Juliette (Georgia) USA are not twins (if anything, their respective families are feuding) but this star-crossed pair issue matching seasonal picture postmarks, as a Shakespearean literary reference on which just the town's name and postcode differ. Valentine's greetings may be stamped, bundled into a larger envelope and sent to the postmaster of either town for re-mailing.

Twin cities
Often, two towns will grow on opposite sites of a common geographic boundary; the Twin Cities of Minneapolis-St. Paul reside on opposite banks of the Mississippi River.

Occasionally, a political boundary on an arbitrary line of latitude or longitude or along a waterway will inadvertently slice through the heart of an existing community, such as the Alberta-Saskatchewan boundary through the unified municipality of Lloydminster. A unified Lloydminster-style city across a provincial boundary is exceptional; most often, a boundary forces creation of two separate, adjacent, geographically contiguous towns or villages. Beebe Plain cannot be a single unified village if, instead of being primarily in Quebec, surveyors' error placed half the unincorporated village in Vermont – in another country. Baarle is divided between Belgium and the Netherlands because of medieval agreements, land-swaps and sales, with the border even running through houses, but is still politically two entities.

In many cases, a pair of twin cities are tightly integrated economically despite maintaining separate, individual identities. This can be the case even across national borders, such as Baarle above or Tornio and Haparanda in Finland and Sweden. The Nordic passport union has since the 1950s allowed nationals to freely pass the border and work (or live) on the foreign side, and the towns have made full use of this.

Twin cities are not mere suburbs; the latter are plentiful and largely non-notable. These are pairs of independent free-standing communities of at least roughly comparable stature which each have their own separate, extensive and long-established identity and history.

Argentina

 * Parana, Entre Ríos and Santa Fe, Santa Fe Province are the capitals of their respective provinces and are separated by the Parana River (which is the Santa Fe-Entre Ríos border).

Australia

 * Albury-Wodonga – a pair on the New South Wales-Victoria border, separated by the Murray River

Brazil

 * Juazeiro, Bahia and Petrolina, Pernambuco are separated by Rio Sao Francisco which is also the state line between Bahia and Pernambuco.
 * Olinda and Recife, Pernambuco
 * Vitória and Vila Velha, Espírito Santo

Canada

 * Kitchener-Waterloo (Ontario) — a pair of southwestern Ontario cities
 * Ottawa-Gatineau — a pair on the Ontario-Québec border, famous as the tulip capital of Canada

Germany

 * Mainz and Wiesbaden, capitals of the German states of Hesse and Rhineland-Palatinate, separated by the river Rhine; two Mainz neighborhoods were ceded to Wiesbaden as a result of redrawn borders following WWII
 * Mannheim and Ludwigshafen in Germany, separated by the river Rhine.

India

 * Ahmedabad and Gandhinagar in Gujarat; Ahmedabad is the largest city in Gujarat, while Gandhinagar is the state capital.
 * Hubli and Dharwad in Karnataka
 * Kolkata and Howrah in West Bengal, separated by the Hooghly River.
 * Mumbai and Navi Mumbai in Maharashtra, separated by Thane Creek.

United States of America
American twin cities that share the same name are not listed here; see the Cross-border town naming section, below.


 * Minneapolis-St. Paul — a pair of Minnesota cities, the most commonly known Twin Cities
 * Champaign-Urbana and Bloomington-Normal in Illinois
 * Dallas and Fort Worth, Texas as the core of the greater Dallas Fort Worth Metroplex
 * Duluth, Minnesota and Superior, Wisconsin are separated by the St Louis Bay and the Minnesota-Wisconsin border that runs through the St Louis Bay.
 * Lewiston–Auburn on opposite sides of a river in Maine.
 * The Quad Cities comprise multiple municipalities on both sides of the Iowa-Illinois border
 * Portland-Vancouver forms the greater "Portland Metropolitan Area", are separated by the Columbia River which defines the Oregon-Washington state border.
 * St Petersburg, Tampa, Bradenton and Sarasota, Florida makes up a quad city metroplex that surround Tampa Bay and is sometimes referred to as "Tampa Bay Area"
 * San Francisco, Oakland and San Jose make up a greater tri-city metroplex known as the "San Francisco Bay Area" as they surround the San Francisco Bay and are connected to each other by a series of roads, railways, tunnels and bridges.
 * Seattle and Tacoma, Washington are 35 miles apart but share an airport known as "SeaTac"; the local airport's community name is short for "Seattle-Tacoma".
 * Tri-Cities, Washington comprise of Pasco, Richland and Kennewick located on the convergence of the Columbia and Snake Rivers in the Columbia River Plateau region of Washington state.
 * Winston-Salem, North Carolina
 * Colorado City-Hildale on opposite sides of the Arizona-Utah border.
 * Ocean City-Fenwick Island in the Delmarva Peninsula, on opposite sides of the Maryland-Delaware border.

Transnational

 * Bratislava, the capital of Slovakia, and Vienna, the capital of Austria, are often referred to as Twin Cities despite their centres being from each other. Nevertheless, they are the closest located national capitals in Europe (if one does not count the Vatican that is within Rome) and form a joint economic region. Two other national capitals not far from each other are  Helsinki and Tallinn, separated by the  wide Gulf of Finland. There are frequent Ferries between the two cities and a long-standing plan to connect them via tunnel.
 * Brazzaville and Kinshasa on the opposite banks of the Congo river are other places where you can be in one national capital and see another.
 * Ciudad del Este, Paraguay; Foz do Iguaçu, Brazil; and Puerto Iguazú, Argentina are on opposite sides of Rio Iguazú and Rio Parana from each other. The convergence of Rio Iguazú and Rio Parana also serves as the border between Argentina, Brazil and Paraguay. Rio Iguazú and Iguaçu_Falls divides Brazil from Argentina while Rio Parana divides Brazil from Paraguay.
 * Copenhagen, the capital of Denmark is separated from Malmö, Sweden's third largest city, by the Øresund strait but are connected to each other by a continuous tunnel & bridge with a combined length of 11.5 km made for rail and road traffic. Further north (45 km on the Danish side and 64 km along the Swedish side) along the Øresund lies Elsinore, Denmark and Helsingborg, Sweden which are only connected to each other by ferry.
 * Dammam, the largest city in the Eastern Province of Saudi Arabia and Manama the capital and largest city of Bahrain can be like 'twin cities' despite their centres being from each other. Bahrain Island is connected to Saudi Arabia by a  long causeway which allows for continuous travel (except customs & immigration formalities between the two countries).
 * Dandong, China and Sinuiju, North Korea are on opposite banks of the Yalu River which defines the Chinese-North Korean border. The border continues upstream along the Yalu River to the Paektu Mountains and downstream to the east coast along the Tumen River where there are other lesser known towns directly across the river and border from each other.
 * Detroit and Windsor — a pair on the Ontario-Michigan border, synonymous with the North American auto manufacturing industry
 * Esztergom, Hungary and Štúrovo (Párkány), Slovakia are connected to the each other by the Mária Valéria Bridge spanning over the Danube.
 * Hong Kong and Shenzhen as well as Macau and Zhuhai.
 * Jaigaon, India and Phuentsholing, Bhutan
 * Laufenburg (Germany) is divided from Laufenburg (Switzerland) by the Rhine; Rheinfelden is also Swiss-German.
 * Narva (Estonia) and Ivangorod (Russia), were for most of their history one single city. There's a fort on both sides of the Narva river that forms the border between the countries.
 * Rivera, Uruguay and Santana do Livramento, Brazil, as well as several lesser-known towns on the border between the two countries. In a lot of these towns the border is nothing more than a grassy divide between two parallel streets with one side in one country and the opposite in the other.
 * Portions of the US-Mexico Border runs along the Rio Grande, also Texas' southern border, which separates El Paso from Ciudad Juarez; Laredo from Nuevo Laredo; McAllen and Reynosa ; Brownsville from Matamoros and a series of other towns directly across the river and border from each other. On the west end of the Mexican-US border are San Diego and Tijuana.
 * St Louis, France and Basel, Switzerland.
 * Tabatinga and Leticia exist as a contiguous settlement on the same side of the Amazon River but are separated by the Brazilian and Colombian border. The islands in the Amazon River and the opposite bank of the river are in Peru. The Peruvian part of the settlement is on Santa Rosa Island, on the river, next to the Tabatinga/Leticia settlement.
 * Singapore and Johor Bahru (Malaysia)
 * A portion of the Mekong River separates Vientiane the capital of Laos from the northern Thai City of Nong Khai.

Cross-border town naming
In some locations, a pair of towns on opposite sides of the same boundary will have the same or similar names:

Australia

 * Mungindi in New South Wales and Queensland

United States of America

 * Bluefield, West Virginia and Bluefield, Virginia
 * Chicago, Illinois and East Chicago, Indiana
 * Kansas City (Missouri) and Kansas City (Kansas)
 * St. Louis, Missouri and East St. Louis, Illinois
 * Texarkana, Texas and Texarkana, Arkansas

Transnational

 * Chuy, Uruguay and Chuí, Brazil are split by a grassy median between Av Brasil (Uruguay side) and Av Uruguay (Brazilian side) in the middle of town
 * Cieszyn, Poland and Český Těšín, Czech Republic
 * Foz do Iguaçu, Brazil; and Puerto Iguazú, Argentina are on opposite banks of Rio Iguazú which flows into Iguaçu_Falls.
 * Gorizia, Italy and Nova Gorica, Slovenia
 * Herzogenrath, Germany and Kerkrade, Netherlands
 * Laredo (Texas USA) and Nuevo Laredo (Tamaulipas Mexico) are divided by the Rio Grande
 * Niagara Falls is split by the falls and a river as Niagara Falls (Ontario) and Niagara Falls (New York)
 * Nogales is split between Arizona (USA) and Sonora (Mexico) right down International Street
 * Sault Sainte Marie (Ontario) and Sault Sainte Marie (Michigan)
 * Ulm (Baden-Württemberg) and Neu-Ulm (Bavaria), Germany - an international border at the time of the foundation of Neu-Ulm now only the border between two German states
 * Valga, Estonia and Valka, Latvia

Divided cities
Often, a village, town or city existed before the border lines were drawn. On a friendly border this may be harmless; Lloydminster functions as one unified city long after the Northwest Territories was split to form individual provinces including Saskatchewan and Alberta. Conversely, an unfriendly border or occupation zone (or even the front line of an active conflict) can forcibly split a community in two, creating a divided city. It is not uncommon for different sectors of the same city to be under the control of different factions if military conflict is active and ongoing.

Berlin was divided into American, French, British and Russian occupation sectors at the end of World War II in Europe, dividing the city on Cold War NATO-Warsaw Pact boundaries until its 1990 reunification. It functioned as two separate cities. Tiny Mödlareuth, on the then inner-German border between Thuringia and Franconia, was also split in two by a wall.

Jerusalem was once partitioned as the front line of the Arab-Israeli conflict, but is now re-unified.

Sometimes an existing border is redrawn (often following a war) right through an existing town. If both communities are viable, sometimes one or both "halves" will be renamed:
 * Görlitz, Germany and Zgorzelec, Poland were separated through the Oder-Neiße line, which is now an open Schengen border
 * Frankfurt an der Oder and Słubice were likewise separated by the Oder-Neiße line, now an open Schengen border
 * Rafah has neighborhoods in Egypt as well as the Gaza Strip; the border is closed to regular travel most of the time
 * Nicosia has been split in half by the Cyprus conflict with the northern part sometimes being called "Lefkosia". The border is controlled but passable to Cypriots and most visitors nowadays.

In other cases, a change in borders after a war has doomed one or both sides of a divided city. See Ghost towns.

Other

 * Istanbul is divided by the Bosphorus, which at the same time is the border between Europe and Asia. This makes Istanbul the only major city in the world to be located on two continents.