Working with GIS data manually

Let's take a brief look at the process of working with GIS data manually. Before we can begin, there are two things you need to do:

• Obtain some GIS data

• Install the GDAL Python library so that you can read the necessary data files

Let's use the US Census Bureau's website to download a set of vector maps for the various US states. The main site for obtaining GIS data from the US Census Bureau can be found at:

http://www.census.gov/geo/www/tiger

To make things simpler though, let's bypass the website and directly download the file we need from the following link:

http://www2.census.gov/geo/tiger/TIGER2012/STATE/tl_2012_us_state.zip

The resulting file, tl_2009_us_state.zip, should be a ZIP-format archive. After uncompressing the archive, you should have the following files:

• tl_2012_us_state.dbf

• tl_2012_us_state.prj

• tl_2012_us_state.shp

• tl_2012_us_state.shp.xml

• tl_2012_us_state.shx

These files make up a Shapefile containing the outlines of all the US states. Place these files...