This so-called North American Union, it asserts, is part of a larger plot by an amorphous, amoral group of powerful elite — including but not limited to the Council on Foreign Relations, the Trilateral Commission and the Rockefellers — to take over planet Earth. Call it the New World Order.

Some of these theories may sound like cable television chatter, or the synopsis of a Dan Brown bestseller. But Birch leaders say this plot is real, with roots going back more than 200 years to a secret, insidious brotherhood called the Illuminati, and with most American presidents among its many dupes and abettors.

“We’ve always referred to it as a Satanic conspiracy,” said Arthur Thompson, the society’s chief executive, sitting beside an American flag.