What are the oldest international borders in the world?
Explore the world's oldest surviving borders, from Portugal and Spain to Andorra and San Marino, and why their age is difficult to define.
10 min read · English
Articles
32 articles
Why is the border between the United States and Canada so straight?
Discover why much of the US–Canada border follows the 49th parallel, how British-American treaties shaped it, and why the line is not entirely straight.
11 min read · English
Why is Switzerland divided into cantons?
Discover why Switzerland has 26 cantons, how medieval alliances became a federal state, and why cantonal autonomy still shapes the country.
6 min read · English
How and why Republika Srpska became part of Bosnia and Herzegovina
Explore how Yugoslavia's collapse, the Bosnian War and the Dayton Peace Agreement shaped Republika Srpska's place within Bosnia and Herzegovina.
6 min read · English
How and why Northern Ireland became part of the United Kingdom
Discover how Ulster's history, partition in 1921–1922 and the Good Friday Agreement shaped Northern Ireland's position within the United Kingdom.
6 min read · English
Why do so many African borders look so straight?
Explore how colonial diplomacy, surveying and post-independence decisions shaped Africa's straight borders—and why the Berlin Conference is only part of the story.
6 min read · English
How and why Quebec became part of Canada
Trace Quebec's path from New France and British conquest to Confederation in 1867, and explore how language, law and sovereignty debates shaped its place in Canada.
6 min read · English
How and why Texas became part of the United States
Explore how Mexican frontier settlement, slavery, the Texas Revolution and annexation in 1845 brought Texas into the United States and helped trigger war with Mexico.
11 min read · English
How and why Budjak became part of Ukraine
Trace Budjak's history from an Ottoman frontier through Russian and Romanian rule to the Soviet division of Bessarabia and Ukrainian independence in 1991.
6 min read · English
How and why Greenland became part of the Kingdom of Denmark
Trace Greenland's connections with Norway and Denmark, its colonial history, and the development of Home Rule and Self-Government.
10 min read · English
How and why the Faroe Islands became part of Denmark
Discover how Norse settlement, the Denmark–Norway union, the Treaty of Kiel and Faroese Home Rule shaped the islands’ place in the Kingdom of Denmark.
11 min read · English
Why is Korea divided? How the border between North and South Korea was created
Explore how the 1945 occupation zones, Cold War rivalry and Korean War created the border and Demilitarized Zone between North and South Korea.
12 min read · English
Why didn't Moldova reunite with Romania? The historical origins of two separate states
Explore how Russian and Soviet rule, national identity, Transnistria and the choices of 1991 shaped Moldova’s independence from Romania.
13 min read · English
Why was Hungary divided? The Treaty of Trianon and the redrawing of Central Europe
Explore how the collapse of Austria-Hungary and the Treaty of Trianon reshaped Central Europe, divided the Hungarian kingdom and created lasting minority questions.
13 min read · English
Why did Ohio and Michigan nearly go to war? The strange history of the Toledo border
Discover how inaccurate maps, the port of Toledo and the politics of statehood sparked the Toledo War and helped shape Michigan’s Upper Peninsula.
9 min read · English
The Honey War: Why Missouri and Iowa nearly fought over their border
Explore how competing surveys, tax collection and militia mobilization sparked the Honey War, and how the Supreme Court settled the Missouri–Iowa border.
7 min read · English
Why is Ellis Island divided between New York and New Jersey? The strange border hidden inside America's most famous immigration station
Discover how an 1834 compact, artificial land reclamation and a 1998 Supreme Court ruling divided Ellis Island between New York and New Jersey.
8 min read · English
Why does Kentucky have a piece of land cut off from the rest of the state?
Explore how colonial latitude lines, surveying errors and a Mississippi River meander created the Kentucky Bend, an isolated part of Kentucky reached by road through Tennessee.
7 min read · English
Why does Delaware have a circular border? The strange history of the Twelve-Mile Circle
Discover how colonial land grants, the Twelve-Mile Circle and centuries of surveying shaped Delaware’s curved border and the disputed Wedge.
8 min read · English
Why does Massachusetts have a strange notch in Connecticut? The history of the Southwick Jog
Explore how colonial surveying errors, disputes over entire towns and the compromise of 1804 created the Southwick Jog on the Massachusetts–Connecticut border.
8 min read · English
Why does Labrador belong to Newfoundland instead of Quebec? The strange history of Canada's eastern border
Explore how British coastal administration, the 1927 Privy Council ruling and Newfoundland’s entry into Canada shaped the Quebec–Labrador boundary.
8 min read · English
Why did Ontario and Manitoba almost go to war? The strange border dispute over Kenora
Discover how rival police forces, railway expansion and colonial boundary claims turned Kenora into a town governed by both Ontario and Manitoba.
8 min read · English
How was Switzerland formed? From medieval mountain communities to a modern confederation
Trace Switzerland’s formation from medieval Alpine alliances through religious conflicts, Napoleon’s reforms and the federal constitution of 1848.
11 min read · English
How did Prussia become Germany? The rise of Prussia and the unification of the German states
Trace Prussia’s rise, its rivalry with Austria and Bismarck’s wars of unification, and discover why Germany survived the eventual abolition of Prussia.
13 min read · English
How was modern India formed? From British colonial rule to the world's largest democracy
Explore how colonial rule, the independence movement, partition and the integration of princely states shaped modern India and its federal constitution.
13 min read · English
Why is Cyprus divided? The history of the border between northern and southern Cyprus
Explore how colonial rule, competing national movements, the collapse of power-sharing and the events of 1974 created Cyprus’s enduring division and Green Line.
12 min read · English
How did Romania's borders change during the 20th century? From Greater Romania to the modern state
Explore Romania’s changing twentieth-century borders, from the creation of Greater Romania to wartime territorial losses and the postwar settlement.
12 min read · English
Why does Belgium have enclaves inside the Netherlands? The strange border of Baarle
Discover how medieval land ownership created the intricate enclaves of Baarle-Hertog and Baarle-Nassau, where the Belgian–Dutch border crosses streets and buildings.
10 min read · English
Why did India and Bangladesh have enclaves inside each other? The world's strangest border dispute
Explore the origins of the India–Bangladesh enclaves, their impact on residents and the 2015 land boundary agreement that resolved most of this intricate border.
10 min read · English
Why does Namibia have a strange narrow strip? The colonial origins of the Caprivi Strip
Explore the colonial negotiations and ambitions for access to the Zambezi that created Namibia’s Caprivi Strip and shaped its unusual northeastern border.
12 min read · English
Why does nobody claim Bir Tawil? The strange border dispute between Egypt and Sudan
Discover how two competing Egypt–Sudan boundaries left Bir Tawil unclaimed by either state while both seek sovereignty over the Halaib Triangle.
10 min read · English
Why does Afghanistan have a narrow corridor to China? The strange history of the Wakhan border
Explore how the Great Game and imperial boundary agreements created Afghanistan’s Wakhan Corridor, a mountainous buffer extending to China.
12 min read · English