Duke University LibGuides - ArcGIS

Add your own data

If you need to join your own data from a spreadsheet file based on common attributes, wait until after you've merged adjacent layers into a single layer (e.g., don't join data to the Edgecombe Co. attribute table if you plan on later merging it with Nash county in order to analyze the entire MSA). Right click on the layer name, choose Joins and Relates ... Join.

Symbolize variables

Change the Symbology to depict demographic data on the map. Use the layer's Properties dialogue (right-click on the layer's name in the Table of Contents) and choose the Symbology tab. Quantities ... Gradated Color is often useful. You will often want to normalize the value of a variable with a total for that geographic unit (e.g., divide the number of rental units per tract by the total number of housing units per tract to get a ratio).

Open and tweak boundary files

Add layers together:

Add layers together (e.g., if the tracts for each county are a separate layer) to get one layer. Name the unified file with a sensible filename. You can use the Merge tool (in ver. 9, go to Toolbox ... Data Management ... General).

Make a layer smaller:

From a single layer, create a smaller layer with just the features you're interested in (e.g., just the counties in an MSA). See the guide on making layers smaller for several ways of doing this.