Why Cities Are Where They Are

Six towns in Pennsylvania’s Cumberland Valley are spaced almost exactly 10 miles apart. Greencastle, Chambersburg, Shippensburg, Newville, Carlisle, and Mechanicsburg lie between Hagerstown, Maryland, and Harrisburg, Pennsylvania. The distances between neighboring towns vary by no more than approximately one mile.

The towns developed at regular intervals without coordinated planning. All six were founded before the United States existed, when walking was the primary means of local travel. Their spacing reflects the practical limits of transportation and trade.

Five miles was approximately the maximum practical distance people could travel to a market and return in one day. A 10-mile gap between towns meant residents generally needed to travel no more than five miles to their nearest market, leaving enough time to buy or sell goods before walking home.

Rural towns established before automobiles commonly developed about 10–15 miles apart. The video argues that this spacing efficiently distributed markets across agricultural land while keeping them accessible to surrounding communities.

Every town has a geographical area from which it attracts customers. Assuming neighboring towns offer identical goods and services, people generally choose the closest one. These surrounding areas form each town’s economic sphere of influence.

An ideal distribution of equally important towns creates hexagonal market areas. When settlements spread in every direction across uniform land, hexagons represent an efficient way to divide their service areas. The Cumberland Valley’s geography instead encouraged towns to develop along a line.

Everyday businesses can survive with relatively small customer populations. Grocery stores, pharmacies, banks, and restaurants serve needs that arise frequently, allowing them to operate in smaller towns without attracting customers from great distances.

Specialized businesses require larger populations because customers use them less frequently. A mechanic, for example, receives visits less often than a grocery store. Supporting that business therefore requires access to more potential customers.

Some small towns grow into larger service centers because specialized businesses need broader markets. These towns attract customers from surrounding settlements, supporting businesses that could not survive in every village.

Larger service centers must be spaced farther apart than ordinary towns. If they are too close together, their specialized businesses compete for insufficient customers. If they are too far apart, residents face unnecessarily long journeys to obtain services.

Cities emerge at the top of a hierarchy of increasingly specialized settlements. They offer ordinary services alongside facilities that require large customer populations, including luxury automobile dealerships, specialized surgical centers, and airports.

People will travel hundreds of miles for expensive, rare, or highly specialized services. A major medical procedure, international flight, or luxury vehicle purchase can justify a much longer journey than an everyday shopping trip. Consequently, major cities have much larger economic catchment areas.

The same settlement pattern operates within individual cities. Coffee shops can survive within a few blocks of one another because customers purchase coffee frequently, while electronics stores must attract people from a much wider area.

Apple Stores illustrate the population requirements of relatively infrequent purchases. The Trumbull Apple Store in Connecticut lies approximately 20 miles from the New Haven store to the northeast and the Stamford store to the southwest.

The video estimates that approximately 500,000 residents can support one Apple Store. Around half a million people live within a 10-mile radius of the Trumbull location. This provides an illustrative estimate of the population served by one store rather than a universal requirement.

Starbucks locations in Lower Manhattan illustrate the much smaller markets needed for frequent purchases. The video estimates an average separation of approximately 600 feet between Starbucks locations in the area.

Approximately 6,000 people live within a 300-foot radius of a representative Lower Manhattan Starbucks. The video uses this figure to illustrate how a coffee shop can operate with a much smaller local customer population than an Apple Store.

Local income affects how many residents a business needs to survive. Connecticut and New York have relatively high-income populations, meaning fewer potential customers may be needed to generate sufficient spending. Equivalent businesses in rural Kansas could require different population sizes or catchment areas.

Retail location decisions reflect both population and purchasing power. The video notes that Apple and Starbucks tend to establish stores in relatively affluent areas, making the Connecticut and Manhattan examples useful illustrations of their location strategies but not universal population thresholds.

The theoretical arrangement of settlements assumes a geographically and economically uniform world. Its ideal patterns require flat land, no geographical obstacles, similar incomes, equally distributed resources, and no significant social differences. Real settlement patterns differ because these conditions do not exist.

Access to water is presented as one of the strongest influences on city locations. Oceans connect distant markets and allow enormous quantities of cargo to move at comparatively low cost, making coastal locations economically attractive.

Coastal cities generally benefit from lower transportation costs than distant inland cities. The video argues that bringing goods to a settlement 1,000 miles inland is generally more expensive than delivering them to a comparable coastal location.

Six of Europe’s ten largest cities are located within approximately 100 miles of the coast. The video presents this distribution as evidence of the historical importance of maritime access to urban development.

Rivers have been as important as oceans, and potentially more influential, in determining where cities develop. They provide transport connections and access to trade routes, allowing cities to function away from the coastline.

Milan is presented as an unusual European example of a major city without direct ocean or river access. The video identifies Milan as Europe’s 19th-largest city and the largest European city situated neither directly on the coast nor on a river. Even so, it lies approximately 15 miles from a river and 75 miles from the ocean.

Direct access to navigable water was historically essential to the survival and growth of major cities. According to the video, this dependence remained particularly strong until approximately the previous century, before modern transport infrastructure reduced the disadvantage of inland locations.

Fourteen of the world’s fifteen largest cities are described as being within a few dozen miles of the ocean. The video uses this concentration to reinforce the connection between maritime geography and the development of major population centers.

Natural resources provide another powerful reason for cities to develop in particular locations. Settlements historically grew near economically valuable deposits because they served as centers for extracting, processing, manufacturing, and transporting those resources.

Pittsburgh illustrates the historical relationship between natural resources and industrial urban development. Its growth is presented as an example of cities developing near the resources required by their manufacturing and transportation industries.

Modern transportation allows resource-dependent economic centers to develop farther from the resources themselves. Raw materials can be transported from extraction sites, reducing the need for administrative, commercial, and industrial activities to be concentrated directly above deposits.

Dubai illustrates how a city can benefit from a regional resource economy without sitting directly beside its main deposits. The United Arab Emirates’ major oil resources are described as being concentrated closer to Abu Dhabi and the country's southwest than to Dubai.

Dubai grew from approximately 10,000 residents in 1900 to 40,000 in 1960. Its 1900 population was less than half that of Carlisle, Pennsylvania, one of the agricultural towns discussed earlier.

Dubai subsequently grew to more than 2.5 million residents, according to the figures used in the video. Its transformation demonstrates how quickly a comparatively small settlement can become a major international city.

The video attributes much of Dubai’s extraordinary growth to its position as an economic and administrative center for regional oil-related activity. It argues that this role enabled Dubai to grow even faster than Abu Dhabi despite being farther from the UAE's principal oil deposits.

Mountains can both encourage and obstruct urban development. Their effect depends on whether the benefits of protection, resources, or strategic position outweigh the difficulties of transportation, construction, and trade.

Major cities can develop at elevations exceeding 7,000 feet. Mexico City, Bogotá, and Addis Ababa are cited as examples demonstrating that high altitude does not necessarily prevent large-scale urban growth.

Mountainous terrain historically offered cities defensive advantages. Settlements in naturally protected locations could be easier to defend against attack, allowing their inhabitants to devote more resources to development rather than security.

Mountains also create substantial barriers to transportation and territorial expansion. Difficult terrain raises the cost of moving people and goods, potentially delaying the development of settlements beyond mountain ranges.

The Appalachian Mountains constrained the early westward development of the United States. The video describes the range as a major geographical barrier that prevented settlement and urban development from spreading westward as rapidly as they otherwise might have.

In 1800, the United States’ population center remained far to the east despite the country controlling territory farther west. This illustrated the difference between possessing territory and being able to settle and economically develop it.

Improved transportation technology eventually shifted the United States’ population center toward Missouri. The video presents this movement as evidence that infrastructure and technology can gradually overcome major geographical barriers.

Without the Appalachian Mountains, the American Midwest might have urbanized considerably earlier. This is presented as a historical counterfactual: the mountain barrier substantially influenced the timing and geographical direction of American development.

Mineral deposits can attract cities into otherwise difficult mountainous environments. Coal, gold, silver, and other valuable resources provide economic incentives strong enough to compensate for harsh terrain and poor accessibility.

Denver’s population grew approximately 650% between 1870 and 1880. The video links this expansion to the opening of a railway branch connecting Denver with the transcontinental railroad.

Denver became an important transportation gateway for gold miners in the Rocky Mountains. Its rapid growth demonstrates how a city can prosper by connecting resource-producing regions with larger transportation and commercial networks rather than relying solely on extraction within the city itself.

Transportation infrastructure can reverse some of the disadvantages created by geography. Denver's development and the westward expansion of the United States show how new connections can change which locations are commercially viable.

Geographical efficiency does not fully explain the locations of existing cities. The video argues that economically well-positioned cities tend to grow while less advantageous locations may decline, but historical decisions and constraints prevent humanity from always settling in theoretically optimal places.

The video identifies 224 cities worldwide with populations exceeding two million. Mapping these cities reveals major geographical imbalances in the distribution of large urban settlements.

Only 32 of those 224 large cities are located in the Southern Hemisphere. The remaining 192 are in the Northern Hemisphere, illustrating the pronounced concentration of major population centers north of the equator.

The Southern Hemisphere contains approximately 32% of the world's land but only 14% of its cities with more than two million residents. The video argues that differences in available land cannot fully explain the geographical imbalance in major urban development.

The historical concentration of large civilizations in Europe and Asia is presented as an important contributor to modern urban geography. Although humanity likely originated in Africa, the video emphasizes the subsequent concentration of influential civilizations and empires across Eurasia.

The east–west orientation of Eurasia is proposed as one explanation for its historical advantage in developing large civilizations. The argument is that extensive stretches of land at similar latitudes allowed agricultural practices, domesticated animals, and technologies to spread across vast distances.

Climate generally changes more dramatically with latitude than with longitude. Regions located east or west of one another often experience more similar growing conditions than regions separated by equivalent distances north or south, although local geography creates exceptions.

The spread of domesticated plants and animals was fundamental to the development and expansion of early civilizations. Agricultural productivity helped support larger populations, economic specialization, and the technologies associated with increasingly complex societies.

East–west expansion could allow civilizations to reuse established agricultural systems. When neighboring territories had similar climates, crops and domesticated animals could often be introduced without requiring entirely new agricultural practices.

North–south expansion could create additional agricultural obstacles. Civilizations moving into substantially different climates might need to identify or domesticate new plants and animals, making expansion more difficult.

Central America is presented as an example of the disadvantages faced by civilizations developing on narrower, north–south-oriented landmasses. The video argues that a civilization originating there would have relatively limited territory with similar climatic conditions available for expansion.

Eurasia offered thousands of miles of territory with broadly comparable climates along east–west routes. According to the video's theory, this made it easier for agricultural technologies and established crops to spread across large regions.

Four major historical empires are used to illustrate the east–west expansion argument. The Qing dynasty, Abbasid Caliphate, Umayyad Caliphate, and Mongol Empire are identified as four of the largest early empires, all originating in Eurasia and expanding substantially across its east–west axis.

The development of maritime technology allowed later empires to overcome some geographical limitations on expansion. The British, Spanish, and French empires established extensive overseas territories rather than relying exclusively on expansion across neighboring land.

The video links part of the United States’ agricultural development to its climatic similarity with Europe. European crops and farming practices could be transferred to substantial areas of North America, helping European settlement and agricultural production expand.

The concentration of developed former colonies in the Northern Hemisphere is partly attributed to their proximity to Europe. Shorter distances and geographical connections are presented as factors shaping European settlement, colonial expansion, and subsequent economic development.

Australia, New Zealand, and South Africa are presented as important Southern Hemisphere exceptions. The video identifies these former British territories as relatively developed countries despite their distance from Europe.

Climate similarity with Europe is offered as one partial explanation for the development of Australia, New Zealand, and South Africa. The argument is that European agricultural systems and settlement practices could be established more readily in suitable temperate climates than in regions with substantially different conditions.

The video proposes locating a hypothetical single city for all humanity by starting with the world's population distribution. Averaging the geographical locations of people worldwide places the population center in south-central Asia, according to the video.

South-central Asia is consequently presented as a strong candidate for the geographical center of a hypothetical world civilization. The argument combines proximity to existing population concentrations with the advantages previously attributed to Eurasia and the Northern Hemisphere.

The video's ideal city would combine coastal access, a navigable river, and nearby mineral-rich mountains. It suggests locating such a settlement within approximately 100 miles of the ocean to benefit from maritime transportation while retaining access to inland resources.

Dhaka, Bangladesh, is identified as the video's leading candidate for the world's theoretically best city location. Its position in Eurasia, proximity to the Bay of Bengal, river access, and relationship to surrounding resource regions are presented as advantages.

Dhaka's geographical position is argued to combine several conditions favorable to major urban development. The video considers its proximity to population concentrations, navigable waterways, maritime connections, and inland resources unusually advantageous.

Dhaka is described as ranking between fourth and eighteenth among the world's largest metropolitan areas, depending on the definition used. The wide ranking range reflects differences in how metropolitan boundaries and populations are measured.

Bangladesh is described as the world's sixth-most densely populated country. The video gives its population as approximately 161 million people living in a country about the size of England, using the population concentration as supporting evidence for the region's geographical advantages.

Dhaka's large population is presented as evidence consistent with the city's favorable location, rather than proof that geography alone determines urban success. Historical, economic, and political circumstances also influence whether geographical advantages translate into development.

Historical events have substantially altered the distribution of the world's largest and most developed civilizations. The video acknowledges that contemporary urban geography does not simply reflect where cities would develop if decisions were made solely according to natural conditions.

The video concludes that south-central Asia might become the center of human civilization if history began again under the same geographical conditions. Dhaka is offered as a particularly strong hypothetical candidate, although the argument remains a geographical thought experiment rather than a demonstrated prediction.