Monthly Archives: June 2013

Mapping Voting Rights Act Section Five Locations

This summer, a couple of us in the DSSC have decided to sit down and learn Leaflet & D3. We'll post some of the maps we make in the blog throughout the summer.

I'm grateful to Peter Leonard, the Librarian for Digital Humanities Research at Yale for getting me started on Leaflet at the NYPL Maps Hack 2013 organized by NYPL Labs.

As an exercise, I decided to map out the places no longer covered by the recent Supreme Court decision (PDF) on section four of the Voting Rights Act.

I took the tables on the Dept of Justice section 5 covered jurisdictions page, joined them together with boundaries from the US Census Bureau's TIGER/Line, simplified the shapefiles in QGIS (removed several fields too), exported to GeoJSON and brought the layers into Leaflet.

The map is sitting at a temp location until the bugs get worked out and we can include the maps in CU Spatial blog posts.

As you can see, it's fairly straight forward and includes some modified (simplified?) code from tutorials on the Leaflet site. The color choices came from ColorBrewer.

One thing I think would improve the map a bit would be to be able to click on the word 'townships' in the legend and have it automatically zoom to Michigan since at the starting scale, both townships are difficult to see (same with the three NYC counties).

Eventually, I'll redo this map in D3 because it'll allow me to use a projection better suited for North America.

Eventually we'll put the data into the Spatial Data Catalog, but for now I'm including a link to zip file containing both the shapefiles & geojson layers without proper metadata and a "use at your own risk" disclaimer. If you use it and find any mistakes, please let us know!