>>150718639
The map shows inland water and water boundaries between states, which ends up obliterating Michigan because all of its state borders other than the southern one and the UP one with Wisconsin are water borders. Note that other Great Lake states also have weird borders on that map because their water is included.
If I get bored someday I might redo that map. The projection used makes the northern part of the country look larger than it is compared to the southern part but the equirectangular projection has the advantage of longitude and latitude being straight lines. One thing is for sure, if I use a projection that accommodates the curvature of the Earth, the curve of the latitude line will be pointed to by some clueless anon as being curved to include Missouri in the south east.