Pretty Choropleth using ggplot in R

I think it's a pretty interesting graph. I got the data from the Minnesota Department of Health Website.

First time using ggplot2 in R

I used the packages XML, rgdal, maptools, and ggplot2. From XML I used readHTMLTable and got a bunch of tables from the Star Tribune 100 website. I was able to get the cities from the tables and then I used the census 2010 cities shapefile and subsetted severely by whether the city was in Minnesota and had the same name as a city from the Star Tribune 100.

I now have the points of the cities and the outline of the state of Minnesota.  Next came the hard part. I don't know a ton about Geographical Information Systems or much about Geography so I couldn't tell what coordinate system my two layers were in.  After much stumbling around I realized that the cities were in longitude and latitude and that the outline of the state of Minnesota was in something called UTM. So I used spTransform from rgdal to change coordinate systems from UTM zone 15 to longitude/latitude. After that I plotted using ggplot2 and it seems to work out.

The three dots that seem like they could be artifacts or something are probably Montevideo, Fergus Falls, and Thief River Falls.