Mormons are an odd mix as well. They formed as a religious community in upstate New York in the 1820s (a period that was notable for the rise of evangelism in the United States in general), ran afoul of the local communities and fled to both Missouri and Ohio before finally settling in Nauvoo, Illinois (the governor of Missouri issued an Extermination Order against all Mormons in Missouri). They lived there for a decade before the locals became disgusted with their behavior and attacked the encampment, killing Joseph Smith in the process. Most of the community then moved to Utah, though the practices of polygamy was eventually ended by the mainstream Mormon church in 1890 (prompting many fundamentalist Mormons, including the ancestors of Romney) to move to Mexico.
Consequently, while they started out as a fairly typical Yankee institution, they really fall outside the Red/Blue dichotomy. Mormons have strong social cohesion, but it's primarily between Mormons. They were early abolitionists, but there is a form of religious apartheid within the religion itself that is particularly strong among its more fundamentalist members. The role of polygamy in Mormonism is strong, even though it was eventually abandoned by the LDS church, because it provided a way of increasing the number of Mormons by birth rather than conversion (this is actually characteristic of many young religions - being a descendent of a founder or disciple always carries with it more clout than being a recruit from the outside, and there are definite dynastic characteristics of Mormonism that are no longer true of more mature religions.
If the US were ever to splinter into regions, I see the Mormon portions of Utah closing its borders and becoming an isolationist country, a Mormon Mecca.