Aaron McCown

  1900   1910   1920   1930   1940   1950   1960   1970   1980   1990   2000   2008

   This map shows the total population of the counties for each decade of the 20^th century as well as the first decade of the 21^st century.  The gray counties were created sometime during the decade prior to their coloration.
    NOTE:

• The first counties to amass large populations are in central-southwest Arizona and north-central New Mexico - these are the counties with Phoenix and Albuquerque.
• The counties in eastern New Mexico grow in the 1st half of the 20th century and then shrink in 2nd half.
• Most counties in Arizona have small populations until the late 20th century.  By 2008, almost all have large populations.

Not All Symbols Are Classified Equally

    The above map uses six classes of Graduated Symbols.  This helps us differentiate between counties large and small populations, but does not depict the truly massive size of certain counties’ populations.  The below maps use Proportional Symbols.  These are not based on a classification system, but instead differ in size relative to the largest and smallest populations.  All of the symbols have a unique size.

NOTE: 

• Phoenix/Mesa, Tucson, and Albuquerque are clearly the dominant population centers at present.  No other map visually displays this as well as Proportional Symbols (although Dot Density does give it a run for its money). 
  
• Rapid and substantial population growth in both states since World War II is also quite accentuated with Proportional Symbols.

The next two maps are choropleth maps.  This type of map depicts statistical variation using different colors.

Another way to look at population growth is the percentage of change between decades.

The map below also depicts Population Change, but net gain or loss instead of percentage.

		If you are interested, you can also view these choropleth maps with Google Earth. Simply download this Zip file, extract and Open the file "population change.kmz" in Google Earth
		The Net Loss and Gain Population Change Choropleth map will soon be available, once this error is resolved.

While choropleths do a good job depicting change, they do not inform us about the size the population of a given county.

Enter Dot Density

    In this geography student's opinion, Dot Density maps (as seen below) provide the most information about population change and overall quantities.  As the legend indicates, each dot on the below map represents 200 people.  Although the dots randomly move between layers (decades), one gets a goodsense of the changing densities in each of the counties. 

    Unlike a Proportional or Graduated Symbol map, Dot Density maps allow for other features to be displayed.  Critical to understanding population growth in the arid Southwest is some basic knowledge about the region's hydrology.  Major water features (rivers and reservoirs) are shown, but not well explained.  The difference between the Colorado and the Rio Grande is significant and accordingly, humans utilize these rivers in very different ways.  Water features also add a little topographic element to the map (rivers flow down hill).
    The location of population centers is very important to understanding population change.  While urbanization is a global phenomenon, it is accentuated in arid regions.  It is logistically easier to provide water to a large concentrated population than a widely dispersed one.  How exactly the water gets to the populations is not well depicted.  Three of the four cities depicted are located next to rivers.  But this encourages one to assume that the Phoenix metropolitan area acquires water the same way Albuquerque does - which is not true.  The Central Arizona Project and other major water or “reclamation” projects are simply not shown.  And how does Tucson, the fourth major city depicted, receive it's water?

Additional Influences on Population Change

Air Forces Bases

The American Southwest is somewhat of a Mecca for private and military aviation, as arid environments often have many days of sunshine.  The map below shows the location of all the major US Air Force bases in Arizona and New Mexico.  These bases increase state populations directly and indirectly.  Directly, Air Force Bases are home to large numbers of personnel and their families.  Indirectly, they provide economic opportunities for service industries, which can be the basis for entire communities.

Notice the large gray patches of Government owned land

View Larger Map

A Big Detailed Map!

This map depicts  all sorts of other phenomenon and land-use classifications not discussed.  The tan Native American Reservations and the green National Parks, Forests, and Monuments are going to have unual population densities.