Recently I wanted to organize the 67 counties in Florida into regions that made sense. I wanted these regions to be based off of data.
I decided I could use commuter data from the Census Transportation Planning Package (CTPP) to create a network graph. It would show the migration of workers 16 years and older from the county they reside in to the county the work in. The thought being that counties that share a commuters are economically linked together.
I used Gephi to create the network graph. It was a weighted directional graph. I had Gephi calculate the modularity using the default settings which broke the state up into 7 regions.
I then exported the data out of Gephi and pulled it into R and created a quick map to visualize the regions. At first blush these regions seem to make sense. This may be a good approach to use in the future.