While working on the various Florida redistricting challenges over the past couple years, one of the major tasks was to sort out the source of district shapes in enacted maps from earlier introduced maps and publicly submitted maps. This was not something that could be done, at least easily, through visual inspection – the Florida Senate redistricting site has over 100 maps for download for the congressional plan alone. Additionally, appearances can be deceiving. An extreme example – fictional, but based on something that actually came up – is presented below.
These districts differ massively in shape, but contain the same individuals, save for 20 people – as you can imagine, the population density of the Everglades is pretty low. One can imagine the reverse, as well, where minor geographic changes in dense city areas can have large impacts on the makeup of a district.