Americans living there: 1 million, according to the US State Department
Why it’s easy: It’s cheap! And you can drive there! Besides, if you’ve ever crossed the border legally, you’ve already completed the paperwork for a six-month stay — that placard you once scribbled on a Cancun-bound plane, three nips deep, is a tourist visa that grants you half a year south of the border. You can’t work legally with it, but six months should be plenty of time to pick one of two longer-term options.