Distribution and Spatial Interaction
• Distribution – arrangement of feature in
space…properties of distribution…
o Density: frequency something occurs
• Arithmetic Density: total # of objects in an
area (i.e. pop density – 340/sq km)
• Physiological Density: # of persons per unit of
area suitable agric (i.e. can country feed
itself?)
World Population Density
Distribution (cont’d.)
• Concentration: feature’s spread over
space
o Clustered/agglomerated: objects
close together
o Dispersed/scattered: objects far
apart (see next slide)
• Pattern: geometric arrangement of
objects in space (square, rectangle,
irregular, etc.)
Density and Concentration of Baseball Teams, 1952–
2000
The changing distribution of North American baseball teams
illustrates the differences between density and concentration.
Time Space Convergence
• Time-space convergence
o The rate at which places move closer together in
travel or communication costs
o Results from a decrease in the friction of distance
as space-adjusting technologies have brought
places closer together over time
• Global and local
• Shrinking of space has important
implications
Time-Space Convergence
• Friction of distance – Tobler’s 1st Law of Geog:
everything is related to everything else, but nearer
things are more related than distant things (i.e.
distance itself hinders interaction).
• Leads to distance decay: contact between two
places decreases as distance increases
Discuss
• How much is Distance Decay an issue today? Is this
something geographers might have to re-think?
Quick Write: Think about where people are spaced in
the US. Where are they clustered? Why there?
Where is it dispersed? Why?
Space-Time Compression
1492–1962
The times required to cross the Atlantic, or orbit the Earth, illustrate how
transport improvements have shrunk the world.
Spatial Interaction
o Complementarity: we need each other
• Ex. One area needs houses, other area has the trees for
lumber
o Transferability: cost involved in moving goods from one
place to another
• Cost
• Ability to bear the costs
• Variability
• Space-Time Compression (see next slide)
o Accessibility: is location accessible? Highways, RR,
shipping? Ex: food very expensive in Alaska
DIFFUSION
• Process in which phenomenon (disease, trends,
technology, etc.) spread from one place to
another over time
o Hearth: place of origination
o Diff happens quickly today w/ modern
technology, communication, transportation
o The “S” Curve
Types of Diffusion
• 1.) Relocation Diff: spread b/c people move
• Languages, Money, Aids
• 2.) Expansion Diff: snowball process
o A. Hierarchical diff: top down process
• Fashion, Music
o B. Contagious diff: like a wave without regard to
hierarchy
• Diseases, Fads
o C. Stimulus diff: spread of underlying principle,
even though characteristic itself failed to diffuse
• Settlers in America – tobacco growers
Hierarchical Diffusion
Contagious Diffusion
Hierarchical and Contagious
Stimulus Diffusion