Here is what I do with census type data.
1. Download the data as an excel spreadsheet or csv.
2. Download the shapefile relating to the data granularity (State, County, Zip, or block)
3. Open the spreadsheet data check
A. that there are no blank lines,
B. that there are no extraneous data lines such as summations or superfluous titles
C. column headers in the first row and that they are less than 12 characters with no spaces or special symbols
other than underscore or hyphens
4. Save spreadsheet and import into MS Access. This step allows you to set the datatypes correctly. Excel has it's
own mind when declaring datatypes.
5. In Access, set the datatypes appropriately in table design mode.
6. Save the MS Access database in 2002-2003 format. This will allow you to import table to ArcGIS Desktop in the
next step.
7. Open ArcGIS Desktop and add both the census polygon shapefile and the Access data table. You can add a
base layer first to set the map's coordinate system.
8. Join the data table to the shapefile using a common key such as county, zip or tract.
9. Data>Export the shapefile (now containing joined data) to a new shapefile of your choosing. The shapefile's
coordinate system will be the same as your working map's. At this point you are finished. You do not need to
save the map. The shapefile is saved and available for use as soon as it is exported.
