After my previous post, a number of people contacted me asking how I made the map and if there was an easy way to make it themselves. This is a post for them and anyone else interested in a quick introduction into the world of Geographic Information Software. While some day, I have no doubt Google will take up the challenge of streamlining personalized digital maps, right now, GIS is complicated. But luckily there’s enough open source software and data that no purchases (or piratings) are required.
What you will need:
1. Functioning computer (preferably a Mac to more easily follow this tutorial)
2. NeoOffice, or any other spreadsheet program capable of opening a DBase (.dbf) spreadsheet file. This means no Microsoft Excel. Sorry.
3. Quantum GIS. This is where the computer magic happens. There are many free GIS programs out there, and I have no doubt this one is not the best. It is though the easiest that I’ve found to setup and use.
4. A Shapefile (.shp). This file holds all the data for the polygons that will be drawn in your map. If your map is a coloring book, then this file determines what the map’s outline look like.%
5. A spreadsheet of data. Any data you want. If your map is a coloring book, then this file’s data will determine what the colors used to fill in the map are.#
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If you are a conservative person who does not like government, you should probably stop reading this now. Okay, people alright with a government that does more than just protect private property and borders, luckily for us, the federal government has mapped just about everything there is to map in the United States and made it available to the public for free!
Through the TIGER/Lines database, available for free courtesy of your Federal Census Bureau, users can download national, state, county, and sub-county maps. Explore the site a little bit because this site and its massive amount of free data first made me interested in the possibilities of GIS. If you want to follow along with this tutorial, you’re going to select a state from the drop-down box, then select a county. You’ll notice on the left side of the page that for each level there are at least a dozen different downloadable maps. Ignore them for now.
On this screen, you want to select the map that will display the individual blocks of whichever county you have selected. A block in Census terms is any area of land bounded on all sides by either roads or water or some other impassable feature. To get this map, choose “Block (Census 2000).” We want Census 2000 instead of the current blocks because the data we will be using is from Census 2000. Download it, unzip it, and you’ve got a folder titled “tl_2009_#####_tabblock00″ where ##### is the county identification number. Now you’re good to go!
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Data you’re wondering, where do I find that? Well a great place to start for American demographic data is with American Fact Finder, again courtesy of your Federal government’s Census Bureau. Once you’re on this website, head to the download center (link on the left-side bar of links).
Wow, a whole lot of data again! Isn’t the government great? Let’s select the first link in the list, “Census 2000 Summary File 1 (SF 1) 100-Percent Data.”
Next select All Blocks In A County because you want the data for each and every block within your chosen county. Check the radio button next to “Selected Detailed Tables – up to 50 tables in pipe-delimited format.” Now find your preferred county, and press the GO button.
Finally you get to the fun part, picking out exactly what you want to map. Because we’re interested in mapping out data, we’re going to choose “P3. Race,” but if you want to create another type of map, it’s pretty easy to do by picking a piece of data you are more interested in. When you actually look at the data sets they’re providing, you’ll realize there’s a lot less exciting data than you’d expect. Most downloads are just minor tweaks of other sets. Race and income are the two most likely to yield interesting geographic maps.