Border in the context of Distance marker

The barrios of Puerto Rico are the third-level administrative divisions defined with geographic boundaries serving as the primary legal subdivisions of the 78 municipalities in the archipelago and island of Puerto Rico, an unincorporated territory of the U.S. Amounting to 902 wards or boroughs equivalent to minor civil divisions in the U.S., like cities, townships, and parishes, barrios are under the governmental authority of the popularly elected strong mayor and unicameral legislature governing the municipality within which they are located. Barrios are subdivided into numerous subbarrios, districts, communities, and/or sectors.

Except for San Juan, Ponce, Florida, and Vieques, all municipalities have a barrio equivalent to a downtown area in the U.S. called pueblo, officially known as barrio-pueblo (literally "neighborhood-town"), which typically is the site of the historic Spanish colonial settlement, administrative center, and urban core of the municipality. Of the 902 barrios proper, 828 are barrios and 74 barrios-pueblos.

A stele (/ˈstiːli/ STEE-lee) or stela (/ˈstiːlə/ STEE-lə) is a stone or wooden slab, generally taller than it is wide, erected in the ancient world as a monument. The surface of the stele often has text, ornamentation, or both. These may be inscribed, carved in relief, or painted.

Stelae were created for many reasons. Grave stelae were used for funerary or commemorative purposes. Stelae as slabs of stone would also be used as ancient Greek and Roman government notices or as boundary markers to mark borders or property lines. Stelae were occasionally erected as memorials to battles. For example, along with other memorials, there are more than half-a-dozen steles erected on the battlefield of Waterloo at the locations of notable actions by participants in battle.

A maritime boundary is a conceptual division of Earth's water surface areas using physiographical or geopolitical criteria. As such, it usually bounds areas of exclusive national rights over mineral and biological resources, encompassing maritime features, limits and zones. Generally, a maritime boundary is delineated at a particular distance from a jurisdiction's coastline. Although in some countries the term maritime boundary represents borders of a maritime nation that are recognized by the United Nations Convention on the Law of the Sea, maritime borders usually serve to identify the edge of international waters.

Maritime boundaries exist in the context of territorial waters, contiguous zones, and exclusive economic zones; however, the terminology does not encompass lake or river boundaries, which are considered within the context of land boundaries.

City limits or city boundaries refer to the defined boundary or border of a city. The area within the city limit can be called the city proper. Town limit/boundary and village limit/boundary apply to towns and villages. Similarly, corporate limit is a legal name that refers to the boundary of municipal corporations. In some countries, the limit of a municipality may be expanded through annexation.

Territories of the United States are subnational geographical and political areas governed as administrative divisions and dependent territories under the sovereignty of the United States. Despite all being subject to the constitutional and territorial jurisdiction of the U.S. federal government, territories differ from states and Indian reservations in that they are not inherently sovereign. While states have dual sovereignty and Native American tribes have tribal sovereignty in relation to the federal government, the self-governing powers of territories ultimately derive from the U.S. Congress, as per the Territorial Clause in Article IV of the U.S. Constitution. Territories are classified as "organized" or "unorganized" depending on whether they operate under an organic act, and "incorporated" or "unincorporated" depending on whether the U.S. Constitution applies fully or partially to them. As areas belonging to, but not integral parts of, the U.S., territories are their own distinct nations centered around a collective identity based on their land, history, ethnicity, culture, and language.

All territories of the U.S. are insular areas. The U.S. has sovereignty over three archipelagos or islands in the Caribbean Sea and eleven in the Pacific Ocean. Five territories (American Samoa, Guam, the Northern Mariana Islands, Puerto Rico, and the United States Virgin Islands) are permanently inhabited, unincorporated territories; the other nine are small islands, atolls, and reefs with no native (or permanent) population. Of the 14, only one is classified as an incorporated territory (Palmyra Atoll). Two additional territories (Bajo Nuevo Bank and Serranilla Bank) are claimed by the U.S. but administered by Colombia. Historically, territories were created to administer newly acquired land, and most eventually attained statehood. The most recent territory to become a U.S. state was Hawaii on August 21, 1959.

In the United States, a county or county equivalent is an administrative subdivision of a state or territory, typically with defined geographic boundaries and some level of governmental authority. The term "county" is used in 48 states, while Louisiana and Alaska have functionally equivalent subdivisions called parishes and boroughs, respectively. Counties and other local governments exist as a matter of U.S. state law, so the specific governmental powers of counties may vary widely between the states, with many providing some level of services to civil townships, municipalities, and unincorporated areas. Certain municipalities are in multiple counties. Some municipalities have been consolidated with their county government to form consolidated city-counties or have been legally separated from counties altogether to form independent cities. Conversely, counties in Connecticut and Rhode Island, eight of Massachusetts's 14 counties, and Alaska's Unorganized Borough have no government power, existing only as geographic distinctions.

The United States Census Bureau uses the term "county equivalent" to describe places that are comparable to counties, but called by different names. Louisiana parishes, the organized boroughs of Alaska, independent cities, and the District of Columbia are equivalent to counties for administrative purposes. Alaska's Unorganized Borough is further divided into 11 census areas that are statistically equivalent to counties. In 2024, the U.S. Census Bureau began to also recognize Connecticut's councils of governments, which took over some of the regional powers from the state's former county governments, as county equivalents.

The municipalities of Puerto Rico (Spanish: municipios de Puerto Rico) are second-level administrative divisions defined with geographic boundaries and governmental authority in the archipelago and island of Puerto Rico, an unincorporated territory of the U.S. Amounting to 78 incorporated towns and cities equivalent to U.S. counties, two of which are outside the main island, namely the smaller islands of Vieques and Culebra, the municipalities are governed by a popularly elected strong mayor and unicameral legislature. They are subdivided into 902 barrios, third-level divisions controlled by the municipal government. As a jurisdiction under U.S. sovereignty, Puerto Rico does not have first-level administrative units akin to states or provinces.

The municipalities of Puerto Rico operate under the Municipal Code of Puerto Rico (Law. No. 107 of 2020), which superseded the Autonomous Municipalities Act of Puerto Rico (Law No. 81 of 1991), as established by the Legislative Assembly of Puerto Rico, the governmental body responsible for their organization under Section 1, Article VI of the Constitution of Puerto Rico. Electorally, the municipalities are grouped into eight senatorial districts and forty representative districts, representing roughly equal populations in the Legislative Assembly.

The geography of Puerto Rico encompasses the geographical features of Puerto Rico, a Caribbean archipelagic and island nation centered around a collective identity based on its land, history, ethnicity, culture, and language, and organized as a self-governing unincorporated territory of the United States. Located between the Greater and Lesser Antilles in the northeastern Caribbean Sea, east of Hispaniola, west of Saint Thomas, north of Venezuela, and south of the Puerto Rico Trench, it consists of the eponymous main island of Puerto Rico and 142 smaller islands, islets, and cays, including San Juan Islet in the north, Vieques and Culebra islands in the Virgin Islands, and Palominos island and Icacos cay in La Cordillera nature reserve in the east, Caja de Muertos island in Caja de Muertos reserve, and Caracoles and Media Luna cays in La Parguera reserve in the south, and Mona, Monito, and Desecheo islands in the Mona Passage in the west.

Measuring 177 km (110 mi; 96 nmi) in length and 65 km (40 mi; 35 nmi) in width with a land area of 8,868 sq km (3,424 sq mi), the main island of Puerto Rico is the 4th largest in the Caribbean, 29th in the Americas, and 81st in the world, making it the 170th largest country or dependency by surface area. With 3.2 million residents, it is also the 4th largest in the Caribbean, 4th in the Americas, and 31st in the world, making it the 136th largest country or dependency by population.

An open border is a border that enables free movement of people and often of goods between jurisdictions with no restrictions on movement and is lacking a border control. A border may be an open border due to intentional legislation allowing free movement of people across the border (de jure), or a border may be an open border due to a lack of legal controls, a lack of adequate enforcement or adequate supervision of the border (de facto). An example of the former is the Schengen Agreement between most members of the European Economic Area (EFTA and the EU). An example of the latter has been the border between Bangladesh and India, which is becoming controlled. The term "open borders" applies only to the flow of people, not the flow of goods and services, and only to borders between political jurisdictions, not to mere boundaries of privately owned property.

Open borders are the norm for borders between subdivisions within the boundaries of sovereign states, though some countries do maintain internal border controls (for example between the People's Republic of China mainland and the special administrative regions of Hong Kong and Macau, between the United States and the unincorporated territories of Guam, the Northern Mariana Islands and American Samoa, and the Minor Outlying Islands, or between North Korea's provinces and cities). Open borders are also usual between member states of federations, though (very rarely) movement between member states may be controlled in exceptional circumstances. Federations, confederations and similar multi-national unions typically maintain external border controls through a collective border control system, though they sometimes have open borders with other non-member states through special international agreements – such as between Schengen Agreement countries as mentioned above.

Border control comprises measures taken by governments to monitor and regulate the movement of people, animals, and goods across land, air, and maritime borders. While border control is typically associated with international borders, it also encompasses controls imposed on internal borders within a single state.

Border control measures serve a variety of purposes, ranging from enforcing customs, sanitary and phytosanitary, or biosecurity regulations to restricting migration. While some borders (including most states' internal borders and international borders within the Schengen Area) are open and completely unguarded, others (including the vast majority of borders between countries as well as some internal borders) are subject to some degree of control and may be crossed legally only at designated checkpoints. Border controls in the 21st century are tightly intertwined with intricate systems of travel documents, visas, and increasingly complex policies that vary between countries.

The European Green Belt initiative is a grassroots movement for nature conservation and sustainable development along the corridor of the former Iron Curtain. The term refers to an environmental initiative as well as the area it concerns. The initiative is carried out under the patronage of the International Union for Conservation of Nature and formerly Mikhail Gorbachev. It is the aim of the initiative to create the backbone of an ecological network that runs from the Barents to the Black and Adriatic Seas.

The European Green Belt as an area follows the route of the former Iron Curtain and connects national parks, nature parks, biosphere reserves and transboundary protected areas as well as non-protected valuable habitats along or across the (former) borders.

Denmark is a Nordic country in Northern Europe. It is the metropole and most populous constituent of the Kingdom of Denmark, also known as the Danish Realm, a constitutionally unitary state that includes the autonomous territories of the Faroe Islands and Greenland in the north Atlantic Ocean. Metropolitan Denmark, also called "continental Denmark" or "Denmark proper", consists of the northern Jutland peninsula and an archipelago of 406 islands. It is the southernmost of the Scandinavian countries, lying southwest of Sweden, south of Norway, and north of Germany, with which it shares a short border. Denmark proper is situated between the North Sea to the west and the Baltic Sea to the east.

The Kingdom of Denmark, including the Faroe Islands and Greenland, has roughly 1,400 islands greater than 100 square metres (1,100 sq ft) in area; 443 have been named and 78 are inhabited. Denmark's population is over 6 million (1 May 2025), of which roughly 40% live in Zealand, (Sjælland) the largest and most populated island in Denmark proper; Copenhagen, (København) the capital and largest city of the Danish Realm, is situated on Zealand and Amager and Slotsholmen. Composed mostly of flat, arable land, Denmark is characterised by sandy coasts, low elevation, and a temperate climate. Denmark exercises hegemonic influence in the Danish Realm, devolving powers to the other constituent entities to handle their internal affairs. Home rule was established in the Faroe Islands in 1948; Greenland achieved home rule in 1979 and further autonomy in 2009.

A transboundary river is a river that crosses at least one political border, either a border within a state or an international boundary. Bangladesh has the highest number of these rivers, with at least 58 major rivers that enter the country from the Republic of India, including two of the world's largest rivers, the Brahmaputra and the Ganges. The Naf River is the only river that flows via Bangladesh into Myanmar.

The hydrologic and political effects of rivers that cross significant boundaries are enormous. Rivers have positive effects in that they carry a significant amount of sediment, which aids in building land in estuarine regions. However, this sediment raises the height of riverbeds, thereby causing flooding. International conventions governing water sharing have led to complex political disputes.

The islands in the Pacific Ocean are categorized into three major island groups: Melanesia, Micronesia, and Polynesia. Depending on the context, the term Pacific Islands may refer to one of several concepts: (1) those Pacific islands whose people have Austronesian origins, (2) the Pacific islands once or currently colonized after 1500 CE, (3) the geographical region of Oceania, or (4) any island located in the Pacific Ocean.

This list of islands in the Pacific Ocean is organized by archipelago or political boundary. In order to keep this list of moderate size, the more complete lists for countries with large numbers of small or uninhabited islands have been hyperlinked.

A capital district, capital region, or capital territory is normally a specially designated administrative division where a country's seat of government is located. As such, in a federal model of government, no state or territory has any political or economic advantage relative to the others because of the national capital lying within its borders. A capital territory can be a specific form of federal district.

A distinction should be made between administrative divisions which include national capitals, but have no special designated status legally (for example, Île de France has no distinct quality from other regions of France). Some federal countries (like Belgium and Germany), give their national capitals the status of full, equal federal units.

36°09′18″N 5°20′54″W / 36.154933°N 5.348363°W / 36.154933; -5.348363

The Gibraltar–Spain border is the international boundary between the British Overseas Territory of Gibraltar and the Kingdom of Spain. It is also referred to as "The Fence of Gibraltar" (Spanish: La verja de Gibraltar) or simply "The Fence".

In general, a port of entry (POE) is a place where one may lawfully enter a country. It typically has border security staff and facilities to check passports and visas and to inspect luggage to assure that contraband is not imported. International airports are usually ports of entry, as are road and rail crossings on a land border. Seaports can be used as ports of entry only if a dedicated customs presence is posted there. The choice of whether to become a port of entry is up to the civil authority controlling the port.

Digital currency (digital money, electronic money or electronic currency) is any currency, money, or money-like asset that is primarily managed, stored or exchanged on digital computer systems, especially over the internet. Types of digital currencies include cryptocurrency, virtual currency and central bank digital currency. Digital currency may be recorded on a distributed database on the internet, a centralized electronic computer database owned by a company or bank, within digital files or even on a stored-value card.

Digital currencies exhibit properties similar to traditional currencies, but generally do not have a classical physical form of fiat currency historically that can be held in the hand, like currencies with printed banknotes or minted coins. However, they do have a physical form in an unclassical sense coming from the computer to computer and computer to human interactions and the information and processing power of the servers that store and keep track of money. This unclassical physical form allows nearly instantaneous transactions over the internet and vastly lowers the cost associated with distributing notes and coins: for example, of the types of money in the UK economy, 3% are notes and coins, and 79% as electronic money (in the form of bank deposits). Usually not issued by a governmental body, virtual currencies are not considered a legal tender and they enable ownership transfer across governmental borders.