Obtaining U.S. Census Data via American FactFinder
and Manipulating It in Microsoft Excel for Use in ArcGIS

The U.S. Census Bureau makes a massive amounts of data available via the American FactFinder website.  Data are available for Census 2000, the 1990 Census, the 1997 Economic Census, and 2002 Population Estimates.  Access American FactFinder at:

http://factfinder.census.gov/

Read a brief overview of "Maps in American FactFinder" by clicking on the "MAPS AND GEOGRAPHY" button on the left column of the American FactFinder homepage.

Creating a Map using American FactFinder

After reading the overview, click on the link to "Thematic Maps."  When the main page of Thematic Maps (see screen-captured image below) is opened its default setting is to use Census 2000 Summary File 1 (which they call the "dataset").  

American FactFinder Thematic Maps page

The map being displayed is population density (which they call the "theme") for the U.S. by state (which they call "geography").  A user can change the dataset, the geography, and the theme to meet her/his specific needs.  For example, let's change the geography to Oklahoma by county and then pick another theme (variable) from within this same dataset.  At the top of this page just under the "Thematic Maps" title is the line that begins with "You are here:" (see screen-captured image below).

American FactFinder, You Are Here line
 
Click on the "Geography" link in this line.  In the "Select geographic type" drop-down box choose "State."  Then in the " Select a geographic area and click 'Show Result'" drop-down box choose "Oklahoma" and click the "Show Result" button.  A map of the current theme (population density) is displayed by county for the state of Oklahoma.  Now click on "Themes" in the "You are here" line at the top of the page.  In the "" drop-down box select a variable (theme) that interests you, perhaps "TM-PCT001. Percent of Persons Who Are American Indian Alone: 2000."  Then press the "Show Result" button.  A map of this theme is displayed by county for Oklahoma.  Go to the next paragraph below to learn how to download the dataset.

Downloading Data for Use in Microsoft Excel (spreadsheet) and GIS Software

With the map of interest being displayed click on the "Print/Download" button near the top of the page and select "Download."

American FactFinder, Print/Download Drop Down

A download window appears (see below).

American FactFinder, Download dialog
 
Select download options.  The options include Excel and comma delimited formats and inclusion of descriptive data element names.  These files are sent in compressed (zip) format.  They have to be extracted (uncompressed) using WinZip or a similar compression utility.  Under the Option line try "" and later try downloading without this option.  I recommend that you download in Microsoft Excel format.  When you have chosen your options click 'OK'.  If you are using Netscape as your Internet browser, you will see a pop-up window similar to the one below.  If you're on-campus, it will refer to the compression software that comes with Windows XP.  So instead of "WinZip" it will say something like "Compressed (zipped) Folder."

Downloading zipped files

I recommend that you choose "Save this file to disk" rather than the default which is "Open using Compressed Folder."  You will still need to uncompress or unzip the files once they are saved, but you will have a better chance of saving the files on disk in a folder which you can find later.  Once you have saved the zipped files to your disk, use "Explore" (right click on the "Start" button and choose "Explore").  Navigate to the folder where you stored the downloaded files. Highlight the files (or use the "Edit" command and "Select All" if the downloaded files are the only ones in the folder).  Then click "File" and "Extract Files."  You now have an Excel spreadsheet (attribute or data) file and some "readme" text files (these are metadata which describe the data file).

Working with the Data in Microsoft Excel

The purpose of working with the downloaded data file in Microsoft Excel is to manipulate it into the proper form for use in ArcGIS.  The main things to be accomplished is to make sure there is a variable (column) that can be used to "join" to the attribute table of an existing shapefile in ArcMap so that the data can be mapped.  Then the file must be saved in dBASE format (.dbf) so that it can be read correctly by ArcGIS.  Here are some things that need to be accomplished:
[That should do it.  We'll practice this in class on Wednesday, March 24.]
Revised March 23, 2004.