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Chapter 3 continued, Population Structure
• Age structure of population – an indicator of state of development
• Relationship between age structure and demands for public services (education, health care…..)
• Population pyramids as indicators of age and gender structure of populations – typically constructed around 5 year age cohorts
Rate of Natural Increase – any places in stage 1 demographic transition, what about stages 2 & 3, and
about stage 4?
Washington State Population Pyramids
Population PyramidWA State, 2000
US Census
6% 4% 2% 0% 2% 4% 6%
0 - 45 - 9
10 - 1415 - 1920 - 2425 - 2930 - 3435 - 3940 - 4445 - 4950 - 5455 - 5960 - 6465 - 6970 - 7475 - 7980 - 84
85 +
Males Females
Higher % ofelderly femalesthan males
Relatively evendistribution upto about 50-54, typical of a developed economy
Big agriculture countiesAdams, Grant, Yakima
College counties – Whitman,Kittitas, Whatcom
Retirement counties Jefferson, Pacific, San Juan
Old wheat countiesColumbia, Garfield
Suburbs - Clark, Snohomish
Professional – King
Poor w/few 20’s-40’s: Stevens, Pend Oreille, Ferry
The Baby Boom and Its Impacts• In the U.S., this 90 million mass of people hit the
labor market in the 1960’s, and will be retiring soon (like me)
• The flood of workers is argued to have stimulated entrepreneurship & the demand for new products
• The burden of the baby boom on social service networks is about to be felt
• The baby-boom “echo”• The tempering influence of migration policy: will
we return to a more liberal period post-911?
•Florida argues that theU.S. has reacted to the9/11 terrorist attacks in ways that stifle themovement of the creativeclass to the U.S.• He sees this as a drag onthe U.S. ability toto compete globallyin the development ofleading-edge industries• And U.S. educationalinstitutions are argued tonot be responding withincreased capacity forU.S. citizens
Migration• A change in permanent residence• Migration motivations: push & pull factors• Migration motivations are more than economic:
social and environmental• Scale of movement: from local to interregional to
international – voluntary versus forced (Hurricane Katrina – is this diaspora permanent?
• Historic forced migration – e.g. African slave trade; intranational movements – WW II Jewish –current civil wars in Africa
Economics of Migration: The Samuelson Model
Equilibrium – when wage rate differential equals travel costdifference between regions
Migration Streams Continued
• Lack of convergence in wage rates begets the Samuelson model
• Cultural influences – Europe, Asia, the Americas….. Globally a Tiebout process
• Impact of regulations – US post 9/11
• Historic age selectivity
• Impacts of migration – social conflict; guest worker programs in Europe; welfare gains for in-migrants.
Migration Patterns to the U.S.
Remarkably different origins
Post9-11?
Absolute # into U.S. rising post VietnamWar Era to levels similar to end of 19th Century
Broad Global Flows of Migrants
Clearlya flow from lowerincome tohigher incomelocations:
Is this supportfor the SamuelsonModel?
The Gravity Model: “Social Physics”
Iij = k * PiPj
Dijb
where I is interaction between place i and j,
p(i) and p(j) are populations of places I and j, k is an empirically derived constant,
and D(i,j) is the distance between i and j, raised to an empirically derived constant, b.
• Stewart, Ravenstein, Ullman
Seattle Opera Ring Cycle Doners and Distance (excluding WA)
Seattle - Excluding Washington
0500
10001500
2000250030003500
0 20 40 60
probability of giving to Ring
Dis
tan
ce
Seattle
R-square.04
Seattle Opera Ring Cycle Doners and Distance (with WA)
Seattle - Washington Included
0500
100015002000250030003500
0 0.0001 0.0002
probability of giving to Ring
Dis
tan
ce
Seattle
Washington
R-square.12 WeakBut Highlysignificant
Travel to the 2004 AAG Meetings in Denver
Denver
0
500
1000
1500
2000
2500
3000
3500
0 0.00005 0.0001 0.00015
probability of trip
dis
tan
ce
Denver
Alaska & Hawaii
Colorado
R-square.02
AAG Meetings in Denver, w/o CO, AK, and HI
Denver - W/O CO, AK & HI
0
500
1000
1500
2000
2500
0 20 40 60
probability of trip
dis
tan
ce
Denver
AdjustedR-square-.02
Summary• This chapter provides an overview of population
trends over the long-run• The Industrial Revolution – in different places at
different points in history – has had powerful impacts on population levels
• Migration and natural increase vary in their regional importance over time
• The Malthusian vision of population growth has been largely replaced by demographic transition models
• Population movements are affected by differences in income levels, but also by environment and politics
• The gravity model can be used to model some population movements, and spatial interaction for many phenomena