At any point in time, around 45 million Americans have no health insurance, although only about half of them will have been in this situation for a year or more. About another 20 million formally insured Americans have limited coverage, with many subtle exclusions and coverage caps. About a quarter of these people could probably afford private coverage if it were available on reasonable terms. Most of them, however, are in families headed by one or two low income workers, and they could not afford the $13 000 (£7 000; €10 000) or so that it costs to provide an average family of four with good health care in the United States (and much more if anyone in the family is chronically ill).

If uninsured Americans fall critically ill they usually receive the necessary health care at the nearest hospital. Few of them, however, receive the timely primary care available to insured Americans. Furthermore, many of them are subsequently hounded by doctors, hospitals, or bill collectors over unpaid hospital bills, which pushes a good number of …