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Thematic Maps

Thematic Maps

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Thematic Maps

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  1. Thematic Maps Sandra Yeboa & Willis Holden

  2. What are Thematic Maps & What Do they Do? Maps that… • Accent a particular geographic attribute or relationships between several attributes • Transform geographic data into geographic information • Reveal spatial patterns

  3. Thematic vs. Reference Maps • Highlights geographic distribution of a particular attribute (ex. Population change) • Highlight many features and geographic attributes

  4. Thematic Maps • Characterized by the use of abstract, graphic symbols that represent quantities and qualities that make locations meaningful • Symbols are varied in color, size, and shape to further accentuate spatial patterns • Examples of varied geographic data attributes: counts, density, rates etc.

  5. Counts, Rates, & Densities • Counts: numbers representing people grouped according to population and housing (ex. U.S. census data are reported as grouped counts in geographically similar areas) • Rates: process of dividing one count by another (ex. Women as a percentage of population) • Densities: count divided by geographic area of grouped counts • (ex. Person per square kilometer)

  6. Thematic Mapping:Mapping counts • Simplest way is mapping a symbol for every individual • Cons: complicates things when population is large

  7. Thematic Mapping:Proportional Symbols Map • Also referred to as “graduated symbol maps” • Shows more detail as symbols shows proportional size to counts it represents • Represents larger groups, not individuals

  8. Thematic Mapping:Rates & Densities • Rates can be mapped to show proportional relationship of 2 counts (use of pie charts, bar charts etc.) • Densities are mapped to show relationship of data to geographic area (i.e. – no symbols) (use of choropleth, or “graduated color”, mapping)

  9. Obtaining Thematic Maps • For this project you will need 3 thematic maps. • You must have at least one from American Community Survey and one Decennial Survey Map

  10. Obtaining a Decennial Map • Go to • On the main page in the center column under “Getting detailed data” go to Decennial Census, and click “get data”.

  11. Obtaining Thematic Maps • Click on the 1990 Census Tab • Make sure that 1990 Summary Tape File 1 (STF 1) - 100-Percent data is the dot selected. To the right of this click on Thematic Maps

  12. Obtaining Thematic Maps • The list tab will be selected, and go to select a geographic type and select county. Then select your state from the box below type. Then select the county of your choice. Highlight your county and click “Next”.

  13. Obtaining Thematic Maps • On this screen you can select any feature that you want to have a map created. • Copy this map into FrontPage

  14. Obtaining an American Community Survey Map • Use the fact finder website. • Go to “Fast Access to Information” type in your name of the county and the state it is located.

  15. Obtaining an American Community Survey Map • Click on the “2000” tab. • Here you can choose any of the statistics that have map next to it. • Choose your statistic and click “map”. • Copy this map into FrontPage.

  16. Summary • Thematic maps accent a particular geographic attribute or relationships between several attributes • Symbols on maps are varied in color, size, and shape to further accentuate spatial patterns.

  17. Summary • For this Project you need at least one of each map. (ACS or Decennial) • For an example of what the project looks like go to •

  18. E-mail • •

  19. Works Cited • DiBiase, David (2002) Understanding Geographic Data. Module 6: Census Data. ESRI Virtual Campus Accessed 30 November 2006. • United States Bureau of the Census (2002) American FactFinder. Accessed 30 November 2006.