People sometimes ask me what software I use to make maps. For GIS stuff generally, I like to use QGIS, a free and open source program licensed under the GNU General Public License. I try to use GNU software whenever possible. In addition to being free of charge, I think the GNU movement is a force of good in the world of technology.

Most government and corporate GIS professionals use a commercial proprietary program called ArcGIS for their GIS needs. It is the industry standard in America and much of the rest of the developed world. ArcGIS is powerful, feature-rich, and perhaps a better GIS platform for beginners who hope to develop GIS skills they can use in a professional capacity. But it’s an expensive, proprietary product. Worse, ArcGIS runs only on Microsoft Windows, an operating system many (including myself) would prefer not to use.

ArcGIS is made by a California company called Esri. Esri holds the distinction of having developed the shapefile, a core component of GIS. You will come across Esri shapefiles virtually everywhere in your GIS adventures. We will be using Esri shapefiles in this tutorial, but we won’t be using Esri software.

Step One: Install QGIS

For this tutorial I will be using QGIS 3.10 on a MacBook Pro running macOS Sierra 10.12.6. The current version of QGIS is 3.16, but 3.10 is the newest version that will run on my (older) OS. You can find and download the right version of QGIS for your computer here. Once you’ve downloaded it, follow the installation instructions and install it. When you launch it for the first time, QGIS should open up looking something like this.

 

Step Two: Download the voter precincts shapefile from Pima County and open them in QGIS

Pima County has a geospatial data portal with lots of useful shapefiles. For this project, we’ll be using the “Voter Precincts” shapefile, which can be downloaded here.

Downloading the Voter Precincts shapefile on Pima County's geospatial data portal

Your download will come as a .zip file. When you unzip it, you should see six files with the following extensions: .cpg, .dbf, .prj, .shp, .shx, and .xml. These are the internal components that make up an ESRI shapefile. Don’t worry for now about what these individual files do. QGIS will handle them for you as a single document.

Double-click on the file “Districts_-_Voter_Precincts.shp.” This should cause QGIS to open the file, and should launch the QGIS application if it isn’t already up. You’ll probably get a dialog box asking you to pick a method of converting coordinates between coordinate reference system. The default selection here is fine. Just click OK at the bottom.

Now you should see your shapfile and its features in QGIS’s main window. If for some reason you don’t, try hitting the full zoom button on the toolbar or using <shift-command-F>.

Pima county voting precincts shapefile in QGIS.

This is a good time to start exploring QGIS’s interface and features. Play around with the map and software and try to get a feel for it. Hovering your mouse over any of the buttons will display a description of what that button does. Some important ones to know about:

QGIS "identify features" buttonIdentify features. This button turns your cursor into a selection tool that opens a window displaying the attribute information for whatever geographic feature you click on. It’s an essential tool for exploring shapefiles and the data they contain. Give it a try: just hover over one of the precincts on the map and click.

 

Pan map. You’ve probably seen this familiar “hand” tool on other programs. It does what you’d expect. Click and hold the button down, and the hand “grabs” the map and can then move it around. A useful navigation tool, especially when you’re zoomed in on something and want to look around without zooming out.


Zoom full. This button is especially useful when you’re lost. QGIS makes it easy to zoom in and out of maps (on a Mac you can do this with the two-finger scrolling motion), and sometimes you zoom so far in or out that you can’t see where you are anymore. Hitting this button should take your zoom level back to a full view of your map and center it in your screen.

 

Continue to part two

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