As late as 1939, the United States had a well-developed plan to invade Canada

As late as 1939, the United States had a well-developed plan to invade Canada. In 1935, Congress went so far as to approve $57 million to update the plan and fund the construction “of three military airfields disguised as civilian airports on the Canadian border, which would be used to launch preemptive strikes against Canadian air forces and defenses.”