Wooed north by his wife, who is originally from Prince Edward Island, Dr. Bannon said: “I’m happier here than I’ve ever been. I’ve done so much better here financially.” When he left Florida, his malpractice insurance cost $50,000 annually. On Prince Edward Island, thanks to a provincial government subsidy, his annual cost of $8,000 is reduced to just $1,000 a year.

As a general surgeon still in practice, Dr. Bannon knows Canada’s medical system firsthand. The major differences between the United States and Canada are less medical than cultural, he said, evident in Canadian patients’ tolerance for wait times and moderated expectations of their health care providers. “Canadian systems work because they’ve been regionalized in order to cut costs,” he explained. An American regional hospital will offer a broader menu of services, and “you’ll get those services here, but you’ll have to travel to a larger city for them.” These include M.R.I.s, CT scans and other complex and expensive tests.

Some areas also have very few family physicians able to take on new patients.

Katrina Brogdon, a Texas-born elementary school principal in Whitehorse, a city in northern Canada’s Yukon Territory, has experience with that, with two children active in competitive athletics. Faced with an eight-month wait for an M.R.I. and a two-hour flight to Edmonton or Vancouver to get it, Ms. Brogdon and her daughter, a competitive swimmer, flew to Vancouver on their own. Ms. Brogdon paid $1,000 from her own pocket for quick access to an M.R.I., while their provincial health plan reimbursed them for the airfare, since the specialist was unavailable locally. Her daughter, suffering from shoulder pain, didn’t want to wait any longer for a diagnosis and treatment plan.

Ms. Brogdon’s family also went almost five years without a family physician, relying on walk-in clinics and her hospital’s emergency room, an experience she calls “horrible.”

They are not the only expatriates to take their chances. “We had no physician for three years,” said Elisabeth Burrow, an American who moved back and forth between the United States and Canada for her education and career, and now runs a food company in Fergus, Ontario, about 90 minutes from Toronto. Like Ms. Brogdon, she and her husband used their hospital’s emergency room or traveled to Toronto for care. “The Canadian system isn’t 100 percent foolproof,” she said. “There are waiting lines for some procedures, but they’re trying to address it.”