Borders define geographic boundaries of political entities or legal jurisdictions, such as governments, sovereign states, federated states and other subnational entities. Some borders—such as a state's internal administrative borders, or inter-state borders within the Schengen Area—are open and completely unguarded. Other borders are partially or fully controlled, and may be crossed legally only at designated border checkpoints and border zones may be controlled. Some, mostly contentious, borders may even foster the setting up of buffer zones.
|This section does not cite any references or sources. (May 2013)|
In the past, many borders were not clearly defined lines, but were neutral zones called marchlands. This has been reflected in recent times with the neutral zones that were set up along part of Saudi Arabia's borders with Kuwait and Iraq (however, these zones no longer exist). In modern times, the concept of a marchland has been replaced by that of the clearly defined and demarcated border. For the purposes of border control, airports and seaports are also classed as borders. Most countries have some form of border control to restrict or limit the movement of people, animals, plants, and goods into or out of the country. Under international law, each country is generally permitted to define the conditions that have to be met by a person to legally cross its borders by its own laws, and to prevent persons from crossing its border when this happens in violation of those laws.
Some borders require presentation of legal paperwork like passports and visas, or other identity documents to cross borders. To stay or work within a country's borders aliens (foreign persons) may need special immigration documents or permits that authorise them to do so. Having such documents (i.e., visa and passport) however does not automatically guarantee that the alien will be allowed to cross to the other side of the border.
Moving goods across a border often requires the payment of excise tax, often collected by customs officials. Animals (and occasionally humans) moving across borders may need to go into quarantine to prevent the spread of exotic or infectious diseases. Most countries prohibit carrying illegal drugs or endangered animals across their borders. Moving goods, animals or people illegally across a border, without declaring them, seeking permission, or deliberately evading official inspection constitutes smuggling.
In regions where smuggling, migration, and infiltration are a problem, many countries fortify borders with fences and barriers and institute formal border control procedures. Some borders are only signposted. This is common in countries within the European Schengen Area and on rural sections of the Canada–United States border. Borders may even be completely unmarked, a common occurrence with remote or forested borders. In many areas, like Africa these are called Porous Borders. Migration within territorial borders, and outside of them, represented an old and established pattern of movement by people in African countries, who were in search of work, food, and who were maintaining ties with kin who had moved across the previously porous borders of their homelands. When the colonial frontiers were drawn, Western countries attempted to obtain a monopoly on the recruitment of labor in many African countries, which altered the practical and institutional context in which the old migration patterns had been followed, and some might argue, are still followed today. The frontiers were particularly porous from the point of view of the physical movement of migrants, and people living in borderland communities easily maintained transnational cultural and social networks.
Natural borders 
Natural borders are geographical features that present natural obstacles to communication and transport. Existing political borders are often a formalization of these historical, natural obstacles.
Some geographical features that often constitute natural borders are:
- Oceans: oceans create very costly natural borders. Very few nation states span more than one continent. Only very large and resource-rich states are able to sustain the costs of governance across oceans for longer periods of time.
- Rivers: some political borders have been formalized along natural borders formed by rivers. Some examples are; the Niagara River border (Canada-USA), the Rio Grande border (Mexico-USA), the Rhine border (France-Germany), and the Mekong border (Thailand-Laos)
- Lakes: larger lakes create natural borders. One example is the natural border created by Lake Tanganyika (DR Congo-Burundi-Tanzania-Zambia)
- Forests: denser jungles or forests can create strong natural borders. One example of a natural forest border is the Amazon rain forest (Colombia-Venezuela-Guyana-Brazil-Bolivia-Peru)
- Mountain ranges: research on borders suggests that mountains have especially strong effects as natural borders. Many nations in Europe and Asia have had their political borders defined along mountain ranges.
Throughout history, technological advances have reduced the costs of transport and communication across these natural borders. This has reduced the significance of natural borders over time. As a result, political borders that have been formalized more recently — such as those in Africa or Americas — typically conform less to natural borders than very old borders — such as those in Europe or Asia — do. States whose borders conform to natural borders are, for similar reasons, more likely to be strong nation-states.
Maritime borders 
A maritime border is a division enclosing an area in the ocean where a nation has exclusive rights over the mineral and biological resources, encompassing maritime features, limits and zones. Maritime borders represent the jurisdictional borders of a maritime nation and are recognized by the United Nations Convention on the Law of the Sea.
Maritime borders 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.
Some maritime borders have remained indeterminate despite efforts to clarify them. This is explained by an array of factors, some of which illustrate regional problems.
Border economics 
The presence of borders often fosters certain economic features or anomalies. Wherever two jurisdictions come into contact, special economic opportunities arise for border trade. Smuggling provides a classic case; contrariwise, a border region may flourish on the provision of excise or of import–export services — legal or quasi-legal, corrupt or legitimate. Different regulations on either side of a border may encourage services to position themselves at or near that border: thus the provision of pornography, of prostitution, of alcohol and/or of narcotics may cluster around borders, city limits, county lines, ports and airports. In a more planned and official context, Special Economic Zones (SEZs) often tend to cluster near borders or ports.
Even if the goods are not perceived to be undesirable, states will still seek to document and regulate the cross-border trade in order to collect tariffs and benefit from foreign currency exchange revenues. Thus, there is the concept unofficial trade in goods otherwise legal; for example, the cross-border trade in livestock by pastoralists in the Horn of Africa. Ethiopia sells an estimated $250 to $300 million of livestock to Somalia, Kenya and Djibouti every year unofficially, over 100 times the official estimate.
Human economic traffic across borders (apart from kidnapping), may involve mass commuting between workplaces and residential settlements. The removal of internal barriers to commerce, as in France after the French Revolution or in Europe since the 1940s, de-emphasises border-based economic activity and fosters free trade. Euroregions are similar official structures built around commuting across boundary.
In much of Europe, such controls were abolished by the Schengen Agreement and subsequent European Union legislation. Since the Treaty of Amsterdam, the competence to pass laws on crossing internal and external borders within the European Union and the associated Schengen States (Iceland, Norway, Switzerland, and Liechtenstein) lies exclusively within the jurisdiction of the European Union, except where states have used a specific right to opt-out (United Kingdom and Ireland, which maintain a common travel area amongst themselves). For details, see Schengen Area.
The United States has notably increased measures taken in border control on the Canada–United States border and the United States–Mexico border during its War on Terrorism (See Shantz 2010). One American writer has said that the 3,600 km (2,200 mi) US-Mexico border is probably "the world's longest boundary between a First World and Third World country."
Historic borders such as the Great Wall of China, the Maginot Line, and Hadrian's Wall have played a great many roles and been marked in different ways. While the stone walls, the Great Wall of China and the Roman Hadrian's Wall in Britain had military functions, the entirety of the Roman borders were very porous, which encouraged Roman economic activity with neighbors. On the other hand, a border like the Maginot Line was entirely military and was meant to prevent any access in what was to be World War II to France by its neighbor, Germany. Germany ended up going around the Maginot Line through Belgium just as it had done in World War I.
Cross-border regions 
Macro-regional integration initiatives, such as the European Union and NAFTA, have spurred the establishment of cross-border regions. These are initiatives driven by local or regional authorities, aimed at dealing with local border-transcending problems such as transport and environmental degradation. Many cross-border regions are also active in encouraging intercultural communication and dialogue as well as cross-border economic development strategies.
In Europe, the European Union provides financial support to cross-border regions via its Interreg programme. The Council of Europe has issued the Outline Convention on Transfrontier Co-operation, providing a legal framework for cross-border co-operation even though it is in practice rarely used by Euroregions.
Border studies 
There has been a renaissance in the study of borders during the past two decades, partially from creation of a counter narrative to notions of a borderless world that have been advanced as part of globalization theory. Examples of recent initiatives are the Border Regions in Transition network of scholars, the International Boundaries Research Unit at the University of Durham, the Association of Borderlands Studies based in North America, the African Borderlands Research Network (ABORNE) and the founding of smaller border research centres at Nijmegen and Queen's University Belfast.
Image gallery 
The following pictures show in how many different ways international and regional borders can be closed off, monitored, at least marked as such, or simply unremarkable.
See also 
|Wikimedia Commons has media related to: Border|
- Border control
- List of countries and territories by land and maritime borders
- List of countries that border only one other country
- List of international border rivers
- List of land border lengths
- List of bordering countries with greatest differences in GDP (PPP) per person
- List of land borders by date of establishment
- List of national border changes since World War I
- List of sets of four countries that border one another
- Political geography
- Political science
- VLIZ Maritime Boundaries Geodatabase, General info; retrieved 19 November 2010
- Geoscience Australia, Maritime definitions; retrieved 19 November 2010
- United States Department of State, Maritime boundaries; retrieved 19 November 2010.
- Valencia, Mark J. (2001). Maritime Regime Building: Lessons Learned and Their Relevance for Northeast Asia, pp. 149-166. at Google Books
- Pavanello, Sara 2010. Working across borders - Harnessing the potential of cross-border activities to improve livelihood security in the Horn of Africa drylands. London: Overseas Development Institute
- Murphy, Cullen. Roman Empire: gold standard of immigration. Los Angeles Times, June 16, 2007 (accessed here June 20, 2007)
- Murphy 2007
- Perkmann, M, Building governance institutions across European borders, Regional Studies, 1999, Vol: 33, Pages: 657 - 667, hdl.handle.net
- D. Newman & A. Paasi, `Fences and neighbours in the post-modern world: boundary narratives in political geography', Progress in Human Geography, 22 (2), 186-207, 1998; D. Newman, "The lines that continue to separate us: Borders in our borderless world", Progress in Human Geography, Vol 30 (2), 1-19, 2006.
- Border Regions in Transition IX Conference, North American and European Border Regions in Comparative Perspective: Markets, States and Border Communities, (January 12-15, 2008) Victoria, BC Canada and Bellingham, WA United States.
- International Boundaries Research Unit, University of Durham.
- Association for Borderland Studies.
- Nijmegen Centre for Border Research.
- Centre for International Borders Research (CIBR) Queen's University Belfast
|Look up border in Wiktionary, the free dictionary.|
- Border Stories - A website devoted to stories from both sides of the U.S. Mexico Border
- Collection of pictures of European borders, mainly intra-Schengen borders
- Institut Européen des Itinéraires Culturels homepage
- Border Ireland - database of activities and publications on cross-border co-operation on the island of Ireland since 1980's
- Talking Borders Queen's University Belfast online audio archive
- Gallery of 700 borderpoints in the world