GIS is a method to visualize, manipulate, analyze, and display spatial data. The document discusses population changes from 1990 to 2000 and how this affected congressional reapportionment. It provides instructions on using ArcGIS software to import data, change layer orders of counties, congressional districts, and census tract boundaries, and display presidential vote data by county from 2004.

1. Brief Introduction to GIS

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What is GIS?
• Geographical Information Systems
A method to visualize, manipulate,
analyze, and display spatial data

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Population Changes 1990-2000

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States which gained a seat (or two) after the 2000 census

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States which lost a House seat (or two) after the 2000 Census

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Reapportionment after the 2000 Census

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2000 Presidential vote by state

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1996

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1992

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Using ArcGIS

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Click on ArcCatalog (cabinet file-shaped icon) or Add Data (black cross
with yellow background) to import data.

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ArcCatalog (cabinet file-shaped icon) contains a lot of different kinds of
data. Additional data may be stored on the university’s GIS server.

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Changing layer orders 1) Counties

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Changing layer orders 2) Congressional Districts

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Changing layer orders 3) Census tract boundaries

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Displaying Data using “Symbology”

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Presidential Vote 2004 by County