I just had lengthy reply typed up detailing the historical and geographical context. This post will have to suffice as a tag for when I get home to my desktop.
EDIT: First of all, I'd like to apologize for reanimating this thread but since I did I may as well add some content. I also like the Deadlands system. It has a horror and sanity mechanic built in as well as rules for divine, arcane and spiritual magic.
Here are a few things I've thought of that may need to be taken into account. This is taken off the top of my head mostly so be sure to double check anything you find suspect.
-Slavery: The post revolution and pre-cotton gin slave based economy was not particularly fruitful. While it was certainly sustainable, importation of African slaves had slowed to a trickle. With the cutting off of exportation of crops it's reasonable to assume that slavery would become unfeasible based on economic grounds although this wouldn't immediately end the institution. Furthermore, fighting in the revolution had resulted in many slaves being granted freedom. Many went north while some remained in the south and farmed or practiced a trade. A few even came to be slave owners themselves.
-Debt: The US was under a crippling debt following the revolution. The federal government owed France a great deal of money while the states owed an even greater sum to private citizens and businesses. This created a lack of trust in the government as well as a movement from within the government to default on the debt to prevent speculators from profiting. This could be used as a plot device to reflect how little the populace expects from the government. "You expect them to protect us from that thing? They only gave me a promissory note for my horses a few years ago and haven't actually paid yet."