I didn't start out believing that secession of 11 western US states was a good thing. I didn't start down the path that led me to that conclusion thinking about matters of secession at all. I was thinking about several long-term trends related to energy supplies, technology, and population. It was only when I began thinking about those trends together that I began to see a longish-term future (25 to 50 years) where a partition of the United States looked like a sane -- and desirable from some perspectives -- thing to do. This post identifies the major trends, which will be expanded on in later posts. Those posts will also explain why I think the trends work together to lead to major changes.
The first trend is the decline in availability of liquid hydrocarbon fuels at affordable prices. I am not, in the vernacular, a Peak Oil "doomer": I don't believe that decreasing availability of liquid hydrocarbons will lead to a global collapse of civilization. OTOH, I do think that decreasing availability will lead to some dramatic changes in how the US looks at the world, and because the country is so large in a geographic sense, at itself. The changes will make the world a bigger place, and the US role in it smaller. Similarly, the US will also become a bigger place, with reduced linkages between different geographic parts of the country.
The second trend is the maintenance of the US electric grid. I am an unabashed fan of modern technology and want to see large parts of it preserved. The energy source that modern technology depends on most is electricity. Failure to provide robust reliable electricity supplies would render much of that technology unusable (eg, it's much more common to see articles that "developing country X's modernization attempts hampered by erratic electricity supplies" than to see that they're being crippled by higher oil prices). I believe that US electricity supplies face substantial challenges in the future, and that the responses to those challenges will have to be regional in nature. When policy makers think about "our" solutions to the electricity supply problem, those solutions will be different. In some ways, the policy decisions will create significant frictions between different parts of the country.
A third trend is the depopulation of the US Great Plains region. The population of the Great Plains counties peaked in the 1930s and has been declining ever since. In the last decade, the trend appears to have reached the point of positive feedback. The declining population has made it more and more difficult to support modern infrastructure and services, which in turn both drives more people out and makes it harder to attract new people, which makes it harder to support services,... An increasingly-empty 500-mile-wide buffer between the East and West portions of the US will lead to a decrease in "national" identity and increase in "regional" identity.
Another trend is global warming. I'm not going to bother with the "climate change" weasel wording: the important consequences of the changes for my purposes are a modest steady warming and effective drying of the US climate, particularly across the southern tiers of states. Warming (and more importantly, drying) will have multiple impacts that are worth exploring. By making agriculture more difficult in the southern Great Plains, it accelerates the depopulation. The problems that the already-arid Southwest will face will be different than those of the humid Southeast. As with some of the other trends, the result will be another factor pushing two parts of the country apart in terms of the policies that they will wish to pursue.
I believe that there are, for geographic and historical reasons, fundamental differences in the parts of the US that are east of the Great Plains and those to the west. One of the obvious geographic differences is illustrated in the map shown at the beginning of this post: the West is mountainous. As a consequence, it lacks long navigable rivers; the places where large cities can be located are limited; corridors where transportation (of people, good, or energy) can be located are limited. Sometimes those make things harder, but sometimes the limited population distribution makes things easier. In the course of these posts there will a number of maps of the 48 contiguous states along with assertions of differences in East and West.
This is a book-sized topic, so even a series of blog posts can't really do it justice. I'm working ( slowly) on the book.