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The U.S. Census Bureau has created digital data for every county in the United States about geographic features we encounter in our everyday lives: streets and highways, water bodies, major landmarks, railroads, and so forth. It has also created data about features we don't always think about: congressional districts, school districts, traffic zones, census tracts, and so forth. For every county in the United States, there are more than 20 such layers of data available for free download at the ESRI TIGER 2000 site: http://www.esri.com/tiger.
The instructions on this page can help you access and use the data. (You might find it handy to print these instructions.) There are three major processes to go through:
- Accessing the TIGER Data
- Preparing the TIGER Data
- Using the TIGER Data
I. Accessing the TIGER Data
- Begin
- Go to the ESRI TIGER 2000 site: http://www.esri.com/tiger.
- The starting page has links to sites where you'll find some good information about the TIGER data, and includes a link to a site where you'll find extensive documentation about the data.
- When you're ready to download data, click the link to the Preview and Download page.
- Select your state.
You may either click on the map or choose from the pull-down state picker.
- Choose the desired "geography" or "feature."
Decide if you want to download data of several kinds for a single county, or data of a single type for several counties. Choose either the county or the data type desired.
- Select the desired elements.
Using the little check boxes at the left of each item, select the desired items. Note the size of each item, on the right. Everything will end up packaged together for downloading, but keep track of how much you will be downloading, and weigh this against how fast your download speed is. You're also limited to 20MB in a single download. You might want to break large downloads into two or more files, if you have a lot of material to download or your connection is slow. If you want to receive all the items, just click the checkbox for the topmost "all" choice, and note how large the file will be.
- Proceed to download.
When your selection is complete, scroll to the bottom and click the "PROCEED TO DOWNLOAD" button. This tells the server to look at your selection, package up a translation file plus all the files you have chosen, and create a single file for you to download. This will take a minute, so wait for the computer to send you your next instruction.
- Click the "download" button.
Once the server has prepared your data, it will give you the option to download the file. At this point, be conscious of how your browser works. Do you need to click and hold, right-click, or just click? Choose the option that makes it easiest for you to tell the computer, "I want to download this, but I want you to save it in the place I designate with the name I choose." Think about where you want to store the data so you can find it. Once you've made these decisions, click the DOWNLOAD FILE button.
- Set the "target" storage site and name.
Your browser will likely ask you what you want to name the file as you are saving it, and where you want to store it. Note carefully where you want to store it, such as
"C:\TIGER2000\DOWNLOAD".
Navigate to the desired drive and directory, and provide a sensible name, with a ".zip" file extension. You might want to name something according to the state and county, such as "tx_travis.zip", or state and features, such as "mn_railroads.zip". Begin the saving process, and wait for the download to be completed.
- Choose more data or exit.
Once the file is downloaded, you can use your browser to go back to previous screens, even to choose a new state, and repeat the process. Once all your data are downloaded, you have completed the stage for which the browser is necessary.
II. Preparing the TIGER Data
Downloading the data is just the first step in using TIGER data. Next you need to do a two-step decompression, putting files in a place where you can find them.
- Self check: decompression software?
To prepare the TIGER data, you need to use file decompression software that can handle ".ZIP" files. If your computer does not have this software, you can download various versions as evaluation, free, or for purchase.
- Navigate to the downloaded ZIP file.
Using your Windows Explorer or Finder, navigate through your drives and directories to where you stored the ZIP file.
- Double-click the downloaded ZIP file.
If your decompression software is properly installed, double-clicking the file should engage the decompression software. If, instead, your computer asks what you want to do with the file, choose to open the file using the decompression software.
- Extract to the desired folder.
Indicate that you want to extract the files to a particular location. Keep track of where the files are being deposited. You may want to take this time to create and name a special new directory for storage, such as "C:\TIGER2000\EXTRACTED".
- Look at the extracted files.
Navigate to the site holding your newly extracted files. You will find "README.HTML" and one or more ZIP files. Each ZIP file contains the data for a single feature type for a single county.
- Double-click the ZIP file/s and extract to the desired folder.
One by one, double-click and extract the individual ZIP files to create the actual shapefiles. Keep track of where these final files are being deposited. You may want to create and name a special new directory, such as "C:\TIGER2000\FINAL". Note that some ZIP files will create just a single ".DBF" table, while other ZIP files will create three files, with extensions of ".DBF", ".SHP", and ".SHX".
- Look at the README.HTML
There are many files in your final folder. The README.HTML file will help you understand which files provide which data. Note that each file name (e.g., abc12345.shp) consists of letters or numbers including a five-number sequence; this special sequence of numbers represents the county Federal Information Processing Standard (FIPS) code (two numbers for the state and three numbers for the county within the state), followed by the period and extension. The README.HTML file will identify which files relate to specific features or tables.
III. Using the TIGER Data
- Engage GIS software.
Begin ArcView, ArcExplorer Java Edition for Education,or ArcVoyager.
- Open a mapping space.
Either create a new view or work with a pre-existing view. If you are using a pre-existing view, notice if the view is in "decimal degrees" or is "projected". This will help you anticipate what your new data should look like.
- Add the desired theme.
Add themes one by one in the standard fashion, navigating to where you have stored the data and making sure that you are adding "Feature Data Source" files (rather than "Image Data Source" files).
- Zoom to the new theme and turn it on.
One by one, zoom to each individual theme. This will bring you to the scale of the county (counties) added. Click the checkbox to the left of the theme name to turn it on.
- Identify features.
Use the "Identify" tool to see information about single features in each theme. The fields listed in the Identify window will be fields you can use for classification and symbolization purposes.
- Add SF1 or PL94 data tables for BLK, GRP, TRT, PLC.
The "block", "block group", "tract", and "place" shapefiles do not carry much data. Instead, there are separate data tables that can be joined to the shapefiles if you have downloaded these tables and if your software allows joining data tables. Add the tgr##000sf1xxx.dbf data tables, and join these to the attribute tables for the block, group, tract, or place files. In each case, use the field named KEY to join the new data to the proper features in the attribute tables.
- Classify and symbolize the data.
Use standard procedures for choosing the symbolization style for each feature.
- Speed up draw times for streets, blocks, and streams.
Because there are often more than 1000 records in the streets, blocks, and streams layers, it may help to speed their draw times by creating a "Spatial Index." (NOTE: This option is only available using ArcView.)
- Make the desired theme active.
- Open the theme table.
- Click the "SHAPE" field at the far left, darkening the header.
- From the "FIELD" menu, choose "Create Index". If this choice is greyed out and "Remove Index" is listed, the index already exists, so just exit this menu.
Questions? Write to communityatlas@esri.com
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