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?

Cape Verde – high birth rates, low death rates, high natural increase

Chile – Declining Death Rate, declining rate of natural increase

Denmark – low birth and death rates, low rate of natural increase

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-9-11?

•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 – Mexico to US

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.Absolute # into U.S. rising post-VietnamWar era to levels similar to end of 19th century

Remarkably different origins

Broad Global Flows of Migrants

Clearlya flow from lowerincome tohigher incomelocations:

Is this supportfor the SamuelsonModel?

Net Migration Rates for Countries

Latin American Migration to U.S.

Migration to and within Europe

Migration due to

civil strife

Migration among U.S. Census Regions – Much more detail is available

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

Example of Gravity Model: Visitors to Olympic National Park

Olympic National Park, Continued

Olympic National Park, Cont.

Travel to the 2004 AAG Meetings in DenverDenver

0

500

1000

1500

2000

2500

3000

3500

0 0.00005 0.0001 0.00015

probability of trip

dist

ance

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

dist

ance

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