Cartographic Skills Module 7: Choropleth Mapping

Module 7 lab continued the data classification experience started in Module 6 and involved the completion of two choropleth maps.  Both ArcMap and Adobe Illustrator were used to complete the maps, one of which was in color (Change in US Population by State) while the other was in gray scale (Change in US Population by Census Division).  The exercise included using Excel for making calculations and utilizing that information to determine appropriate classification method for the data, selecting appropriate color scheme and grays for the different classes of the choropleth maps, labeling states and divisions, and creating legends.  Being quite fond of Excel for numerous purposes both personally and professionally, I used it beyond the lab requirements to determine additional information for different classification methods which I then used to select a data classification method for the second map.

Percent Change in State Populations (1990 to 2000)

Practicing projections in Introduction to GIS (GIS4043) provided the experience needed to change the projections of Alaska and Hawaii to something which would yield more realistic graphics, specifically for Hawaii.  The nearly North-South orientation of the Aloha State was a bit disconcerting, but reprojection took care of that.

Labeling divisions for the second map was an exercise in experimenting effort.  Several font sizes, types, and effects were attempted in trying to achieve the best, most uniform appearance for the division labels.  The appearance of masking was not appealing, and trying to label enough of the states in each division to distinguish between adjacent divisions which were in the same class (West North Central/East North Central and Middle Atlantic/New England) was a challenge.  Finally I settled on allowing labels to straddle some state lines, but shifted the labels so that the lines were generally between letters or words in the label.  Using Transform > Move allowed very fine movement to do this.

Percent Change in Census Division Populations (1990 to 2000)

The results of the lab assignment are two easy-to-read-and-interpret maps, one for the change in US population for individual states as well as the District of Columbia and another for the change in US population by Census Divisions.