There aren't too many secession movements, even proposed secession movements, in the United States today, which is not really much of a surprise when you consider what was going on a hundred and fifty years ago. Nevertheless, there are a few that, so far purely intellectually, consider the prospect of slipping out of the straitjacket the United States has become.
One of 'em, I can practically see from my front window. The Republic of Cascadia is a concept for an independent state carved out of the Pacific Northwest, echoing the 1970s visions of Ecotopia, generally conceived as a liberal, environmentally-focused state - think Seattle, or at least Seattle as it's commonly perceived, as an entire country. Back in January, TIME Magazine listed Cascadia as one of the Top 10 Aspiring Nations. While the extent of the Republic of Cascadia varies from expounder to expounder, with some including northern California, Idaho, and bits of Montana, generally speaking it's formed around a core of Oregon, Washington... and British Columbia.
Makes it just a bit more complex.
One of the more well-known flags for the prospective Republic of Cascadia. This image was originally created by Lexicon at Wikipedia, and has been made available under the Creative Commons Attribution-Share Alike 2.5 Generic license.
From my perspective, British Columbia's inclusion in Cascadia is, simultaneously, one of the most believable and most questionable aspects of Cascadia. Believable because, well, the idea of British Columbia becoming independent from Canada is actually plausible; Canada recognizes the rights of its provinces to break away should they so desire, whereas the United States recognizes the rights of its states to get crunched up by tanks if they try to break away. Whether or not that would happen is something else again - as far as I'm aware, the modern-day British Columbian separatist movement is effectively nonexistent, whereas you can at least hear whispers of Cascadia every now and then if you listen carefully.
British Columbia could join an independent Cascadia... but would it? The ideal of Cascadia may be one country, but right now it's split across two, and its components face rather different challenges from their respective federal governments. I can easily imagine a situation where the United States rebounds from its current problems while Canada frays at the seams; I can just as easily conceive of a future where the American political situation becomes more and more acrimonious and divisive, and more and more people begin to believe that separation is necessary for prosperity. When I encounter the automatic inclusion of British Columbia into Cascadia, I have to wonder if it doesn't come out of the same wellspring that fueled so much annexationist sentiment in the nineteenth century - the idea that Canadians, as a whole, were only waiting with bated breath for the opportunity to become Americans. Keep in mind that the combined population of Oregon and Washington are double that of British Columbia; if that's the case, it's not hard to imagine that Cascadia would take after the United States far more strongly than it would Canada.
Nevertheless, I've got nothing against the idea of a Republic of Cascadia, independent of both the United States in Canada, in principle. Self-determination is an important thing, and peoples do not create independent states lightly. Still, it would probably mean a hard choice for me if I was still living in New Westminster when that pine tree flag went up the pole. Or perhaps a Cascadia could come about first through an independent British Columbia, and a subsequent fragmentation of the United States leading Washington and Oregon to join up and form it that way.
I think I'd prefer it to the Transhuman Space alternative, where British Columbia ended up shacking up with Alberta. I don't know if I'd like that country quite as much.