Newton’s First Law of Migration:
The Gravity Model
A.K.A. Kuby Snacks: Chapter 4
Places are connected through spatial
interaction…the more connected…the
more we get…???
ideas
information
money
products
people
…Migration
A permanent change in
residence to outside one’s
community of origin.
Occurs at various spatial scales:
rural-to-urban
urban-to-urban
global (between countries)
Where to and Why for??
Factors of Place Desirability?
Less-desirable places
What are some of the "more-desirable places" to
migrate to within your state, country, world?...Why??
What are some of the "less-desirable places" to migrate
to within your state, country, World?...Why
More-desirable places
(p. 88)
immigration = migration across an international border
remittances
18,000,000
16,000,000
14,000,000
12,000,000
10,000,000
8,000,000
6,000,000
4,000,000
2,000,000
0
Latin America
NW Europe
SE Europe
Asia
Africa
Birthplace for foreign born population shows Historical immigration trends
U.S. immigration laws historically favored northwestern Europeans and excluded people from other
regions in the world…Can you tell when those laws changed?
Illegal immigration?? Push and Pull factors??
refugees immigrate unwillingly due to persecution
in their home country
(a PUSH factor)
PUSH factors
PULL factors
high housing costs
better job
traffic gridlock
pleasant physical setting
rising crime rates
affordable housing
War
desirable climate
high tax rates
proximity to family
poor climate
Others??
undesirable job
Migrant Selectivity
Figure 4.4 (p. 92)
How has the friction of distance changed since a
century ago? Why?
Distance Decay/Friction of Distance
Migration Streams
Migration Streams
&
Counterstreams
Ten Largest Domestic
Migration Streams of
Persons Born in Cuba
Ten Largest Domestic
Migration Streams of
Persons Born in Mexico
Figure 4.7 (p. 95)
Mobility
• Part of American experience
• Mobility is high in developed countries
with immigrant background
• Migration in the past as a predictor
of future migration.
Moving to a new home is a common sight
in the highly mobile United
States…Why…When does mobility
Figure 4.9 (p. 99)
increase??? Decrease??
U.S. Mobility Rates…Why are we becoming less mobile?
Figure 4.10 (p. 100)
• Regional and sub-regional shifts in population
• Net migration
• Migration patterns reflect:
- location of states
- historical patterns of movement
- changing economic geography
- perceptions about places
Net migration rates by state…What explains the differences?
Gravity Model: Predicting Migration
Are there other variables than size and distance that affect migration decisions?...k is used to smooth out
the effects of those other variables
(p. 97)
Gravity Model Scatter Diagram
Online Activity
Figure 4.13 (p. 107)
Extreme values to
delete and outliers to
label
Cluster of points
expands when extreme
values are deleted
Figure 4.14 (p. 108)
Newton’s First Law of Migration:
The Gravity Model
Case Study
Remember your Homework for Friday
Read Kuby pp. 88-102 and respond to Questions 1-8
You will complete the Computer activities in class on Friday
And submit your responses to Activities 1-4 on Monday.
Chapter 4
Name That Key Term
Movements of ideas, information, money,
products, and people between places.
Spatial Interaction
A permanent change in residence to
outside one’s community of origin.
Migration
A move across international borders.
Immigration
A person who is outside his or her country
due to a well-founded fear of persecution
and who is unable or unwilling to return.
Refugee
A well-defined migration channel from a
specific origin to a particular destination.
Migration Stream
Migration that runs opposite
to a migration stream.
Migration Counterstream
The tendency for certain types of people
to migrate. Age, education, and other
sociodemographic characteristics are
________ ________ factors.
Migration Selectivity
The percentage gain or loss of population
due to migration. It is calculated as inmigrants minus out-migrants divided by
the total population, all times 100.
Positive numbers indicate net gain;
negative numbers indicate net loss.
Net Migration Rate
Reasons to move from a particular place.
Push Factors
Reasons to move to a particular place.
Pull Factors
Money sent by immigrants from
host country to home country.
Remittances
A scatter of dots showing the relationship
between two variables. Each dot on the
graph represents the x and y coordinates
of a different observation or case.
Scatter Diagram
A model to predict spatial interaction,
where size (population) is directly
related to interaction and distance is
inversely related to interaction.
Gravity Model
A point on a scatter diagram that is
roughly in line with the main trend but is
separated from the main group of points
because of its very high or low value.
Extreme Value
Point on a scatter diagram that lies far off
the trend line. ________ on the graph
correspond to cases that are poorly
predicted by the model. ________ are not
to be confused with extreme values,
which may lie far from any other point but
which are still close to the best-fitting line.
Outlier
The difference between an actual
observed value of some variable and its
predicted value using the gravity model.
Residuals
The declining intensity of an activity with
increasing distance from its point of origin.
Distance Decay