Nine Nations Of North America

Joel Garreau book from 1981 suggesting that there are 9 different regional cultures covering the US, Canada, and Mexico, and that maybe it would make sense to draw national boundaries that way...

http://en.wikipedia.org/wiki/Nine_Nations_of_North_America

http://www.garreau.com/main.cfm?action=book&id=3

Garreau argued that everything from politics to Urban Planning must be redesigned to match the evolving regional or bio-regional sensibilities that now matter more to people than national and international borders..The theory of Bioregional Democracy and Urban Secession owe much to his analysis, as does the theory of Free Trade... A parallel impact has been to cast doubt on the role of American state and Canadian provincial governments, especially vis a vis these keystone cities. (more detailed summary)

or.... Colin Woodard's American Nations: A History of the Eleven Rival Regional Cultures in North America https://www.wideopencountry.com/map-shows-u-s-divided-11-culture-specific-nations/

Related: US population is clustered mostly in 10/11/20 CityRegions/MegaRegions. https://en.wikipedia.org/wiki/Megaregions_of_the_United_States

Or maybe make 50 states of roughly equal population?