Models of urban structure
Urban / Services FYI
• 1. Cities have many issues to deal with >
Race relations
Traffic
Water delivery/ infrastructure
Pollution
Sprawl
• 2. Cities are ranked in a hierarchy: hamlet – megalopolis
• Largest megalopolis in USA = NYC area (Bos – Wash)
• 3. There are only 3 World Cities: NYC, London, Tokyo
• Other cities are ranked based on importance to their service areas (SEP)
• 4. Primate cities have 2x the amt of population as the next largest city in the
same country (London, Paris, Buenos Aires….)
Urban / Services FYI
•
5. The USA has 3 basic models of urban structure:
– Concentric Zones/ Burgess,
– Sectors/Hoyt,
– Multiple Nuclei/ Ullman and Harris
•
•
6. Continents have different urban characteristics:
Europe > older/more historic cities, poor in suburbs, not inner cities…. (Paris…)
•
Asia > cities are built as ports for trade b/c of colonialism (Goa, Mumbai, Singapore…)
•
Latin America > High income houses are built on a spine from the CBD (BA, Sao Paulo, Rio….)
• Africa > 3 separate CBDs:
Colonial, Modern, market zone (pre-colonial) > think about Capetown, SA or cities in Tanzania, etc…
•
•
7. All cities fit w/in Christaller’s central place theory. (more on this later….)
Some have greater ranges and need bigger thresholds.
Burgess – Concentric Zone model
BRING OUT YOUR CHART…
A model describing land uses as a series of circular belts or
rings around a core central business district, each ring
housing a distinct type of land use.
• Studied 1920’s Chicago to make this model
• 5 concentric zones
• Immigrants lived in inner zones causing affluent residents to move further out
Weaknesses
•
•
> does not allow for change in the city
> does not allow for physical geographic barriers like mtns, rivers, etc..
Sector model/Hoyt
A description of urban land uses as wedge-shaped sectors radiating outward from the central
business district along transportation corridors.
• Late 1930’s
• Answered drawbacks of Burgess Model
• Growth creates PIE shaped urban structures
• CBD isn’t as important is Burgess says it was
• Sectors develop along transport routes (hwy, RR, etc…)
The Sector Model -Homer Hoyt (1939)
There tends to be a
filtering down process
as older areas are
abandoned by the
outward movement of
their original inhabitants,
with the lowest-income
population becoming
the dubious
beneficiaries of the least
desirable vacated
areas.
Multiple Nuclei Model – Harris and Ullman
(1945)
The postulate that large
cities develop by peripheral
spread not from one central
business district. There are
several nodes of growth,
each of specialized use.
The separately expanding
use districts eventually
coalesce at their margins.
Urban Realms Model
•
•
•
•
•
•
•
Modeled after L.A. in the 1990’s
Post WWII cities grew increasingly outward
Nuclei or Realms become less dependent on each other, and much less on the CBD
Realms became largely self-sufficient in most cases
Regional shopping centers became like the CBD
Construction ‘ring roads’ created growth explosions at major highway intersections in outer
areas
Leads to emergence of EDGE CITIES (Woodlands in the case of Houston.
Other Urban models info
•
The Galactic City
As suburbs continue to sprawl they
spawn many suburban nucleations,
which are simply multiple downtowns
and special function nodes and
corridors, which are linked by the
metropolitan expressway system.
•
Gentrification
The movement into the inner portions
of American cities of middle- and
upper-income people who replace
low-income populations, rehabilitate
the structures they occupied, and
change the social character of
neighborhoods.
•
Squatter Settlements
An area within a city in a less
developed country in which people
illegally establish residences on land
they do not own or rent and erect
homemade structures.
• Density Gradient
The change in density in an urban
area from the center to the periphery.
Urban Geography
Cities >
The most significant human features on Earth!
Cities must DO something to exist
• What do cities DO? Provide JOBS
and SERVICES
Urban area models –
these are linear/time oriented…
Urban land use patterns…
•
•
•
•
•
Urban geographers study land use, the activities that take place in cities.
Basic land use patterns found in all cities are:
•residential, including single-family housing and apartment buildings
•industrial, areas reserved for manufacturing of goods
•commercial, used for private business and the buying and selling of retail products
• Of course, Houston has no zoning so we don’t fit the urban
patterns as well as other cities….
Things cities DO can be remembered this way >
PIGS
PIGS
• Ports cities > Located on a seacoast or river.
• The city’s economy relies on shipping and trade with other regions.
PIGS
• Industrial cities > These cities have lots of different industries,
factories and offices that provide jobs and services for people
PIGS
• Government cities > Serve people’s political needs as capital of a
state, country, etc…
PIGS
• Specialization of services > Think tourism/fun, finance, education,
religious pilgrimages….
PIGS
• Ports cities > Located on a seacoast or river. The city’s economy
relies on shipping and trade with other regions.
• Industrial cities > These cities have lots of different industries,
factories and offices that provide jobs and services for people
• Government cities > Serve people’s political needs as capital of a
state, country, etc…
• Specialization of services > Think fun, tourism, education, religious
pilgrimages….
Urban Hierarchy
Urban Hierarchy
What is it???
A ranking of cities based on their size and functional complexity.
This allows one to measure the numbers and kinds of functions each
city provides. The hierarchy is like a pyramid with a few large and
complex cities at the top and many smaller, simpler ones at the
bottom.
World Cities
•
•
- The internationally dominant centers that together
control the global systems of finance and commerce.
London, Tokyo, NYC…
•
Note WHERE World Cities are located in a spatial
context….
Primate City –
(Not a city of monkeys…)
A city that is far
more than twice the
size of the second
ranked city.
The capital cities of
many developing
countries display
that kind of
Overwhelming
primacy.
Can you see the primate cities?
Can you see the Hierarchy pattern?
Rank-Size Rule
• Houston
– Katy
• Luling
– Cut N Shoot
• The Rank Size Rule notes the relationship between the ranks of cities and
their populations.
• It was advanced by Zipf in 1941
• The formula is Pn=P1/n where Pn is the population of towns ranked n, P1 is
the population of the largest town and n is the rank of the town.
• For example, if the largest town has a population of x, the second largest
town will have a population of x/2, the 3rd largest will have a population
of x/3 and so on.
• What is the primate city of Tx?
• How does the Rank-size rule show up on this map??
• The Law of the Primate City
– The primate city is the largest most dominant city in a region.
– The degree of primacy refers to the dominance of the largest city
over the rest of the country.
– Most LDCs (Less Developed Countries) have a high degree of
primacy while most MDCs (More Developed Countries) have a
low degree of primacy.
Factors that affect high primacy include
– Having an underdeveloped economy
– Having an agriculturally dominant economy
– A rapidly expanding population
– A recent colonial history
Africa at night – great example of primacy!
Gravity Model
Predicts The Movement of People and Ideas Between
Two Places
•
- Holds that the potential use of a service at a particular
location is directly related to the number of people in
a location and inversely related to the distance
people must travel to reach the service.
• The gravity model was expanded by William J. Reilly in
1931 into Reilly's law of retail gravitation to calculate the
breaking point between two places where customers will
be drawn to one or another of two competing commercial
centers.
Opponents of the gravity model explain that it can not be
confirmed scientifically,
> That it's only based on observation.
• They also state that the gravity model is an unfair method
of predicting movement
• because its biased toward historic ties and toward the
largest population centers.
• Thus, it can be used to perpetuate the status quo.
•
•
The gravity model was created to anticipate migration between cities (and we can expect that more
people migrate between LA and NYC than between El Paso and Tucson),
it can also be used to anticipate
– the traffic between two places,
– the number of telephone calls,
– the transportation of goods and mail,
– and other types of movement between places.
– The gravity model can also be used to compare the gravitational attraction between two continents, two
countries, two states, two counties, or even two neighborhoods within the same city.
Gravity Model Math…
• Compare the bond between the New York and Los Angeles
metropolitan areas >
– first multiply their 1998 populations (20,124,377 and 15,781,273,
respectively) to get 317,588,287,391,921
– divide that number by the distance (2462 miles) squared (6,061,444).
– The result is 52,394,823.
– We can shorten our math by reducing the numbers to the millions place 20.12 times 15.78 equals 317.5 and then divide by 6 with a result of 52.9.
More GM math…
• Try two metropolitan areas a bit closer El Paso (Texas) and
Tucson (Arizona). Multiply their populations (703,127 and 790,755)
to get 556,001,190,885 and then Divide that number by the
distance (263 miles) squared (69,169) and the result is 8,038,300.
• Therefore, the bond between New York and Los Angeles is greater
than that of El Paso and Tucson!
• How about El Paso and Los Angeles? They're 712 miles
apart, 2.7 times farther than El Paso and Tucson! Well,
Los Angeles is so large that it provides a huge gravitational
force for El Paso. Their relative force is 21,888,491, a
surprising 2.7 times greater than the gravitational force
between El Paso and Tucson! (The repetition of 2.7 is
simply a coincidence.)
Central Place
- An urban or other settlement node whose primary function
is to provide goods and services to the consuming
population of its hinterland, complementary region, or trade
area. Also known as a market center.
Central Place
•
•
•
A Central Place is a settlement which provides one or more services for the population living
around it.
Simple basic services (e.g. grocery stores) are said to be of low order while specialized services (e.g.
universities) are said to be of high order.
Having a high order service implies there are low order services around it, but not vice versa.
Settlements which provide low order services are said to be low order settlements.
Settlements that provide high order services are said to be high order settlements.
The sphere of influence is the area of under influence of the Central Place.
The minimum population size required to profitably maintain a service is the threshold population.
•
•
•
•
Factors affecting a fall in the threshold population are
A decrease in population
Change in tastes
Introduction of substitutes
•
•
•
Conclusions That Can be Made About Central Places
• The larger the settlements, the fewer their number
• The larger a settlement, the farther away a similar size
settlement is
• The Range increases as the population increases
• The larger the settlement, the higher the order of its services.
Deviations to this rule are:
– Tourist resorts that have a small population but large
number of functions.
– Dormitory towns that have a large population but a small
number of functions.
Central Business District (CBD)
•
- The nucleus or “downtown” of a city
•
where retail stores, offices, and cultural activities are concentrated,
•
mass transit systems converge
•
land values and building densities are high.
• Because the CBD’s accessibility produces extreme competition for the limited
sites available the land value is very high.
• Due to the high cost of the land manufacturing and residence are excluded
from CBD’s.
Central Place Theory
Or….
Why doesn’t McDonalds have to put restaurants on corner lots????
(ie at peak value intersections)



CENTRAL PLACE THEORY
Walter Christaller, Germany, 1933
•
•

“A general deductive theory for the purpose of explaining the
size, number and distribution of towns.”
Based on his studies of southern Germany, Christaller wanted
to explain the relative size and spacing of towns and cities
as a function of people's shopping behavior.
In 1950 Christaller made this statement:
“When we connect the metropolitan areas with each other through lines,

and draw such a network of systems on the map of Europe, it indeed
becomes eminently clear how the metropolitan areas everywhere lie in
hexagonal arrangements.”
Assumptions
>Region is flat and there are no physical barriers
>Soil fertility is uniform
>There is an even distribution of population and
purchasing power
>Equal access to transportation
>Constant maximum distance/range for sale of any
good or service radiates
out from the center.





Threshold and Range > CPT is built on these
concepts.

1. >> Every person makes shopping decisions within
a framework of how far they would travel (range) to
buy the desired good or service.

2. >>A city will be located at the center of the
minimum total travel for the area it serves, hence
Central Place.
Threshold and Range >

3. >>According to this cities are distributed across space
based on the size of their market, illustrating the bond
between city function and settlement size and the relationship
between a city and the population around it.



Low range goods = not willing to travel very far
High range goods = items or services you are willing to drive a long
distance to procure.
Threshold = minimum number of people a firm would need to support
its economic operation.