SOME 35 MILLION Americans go without health insurance of any sort, and that number is steadily rising. Typically, they are not destitute or unemployed. Few of those uninsured people are rich, but two-thirds of them are in families with incomes above the poverty line. More than half are full-time workers and their dependents. This huge gap in the health insurance structure can't be patched merely by expanding welfare provisions, for most of the people without coverage are not eligible for welfare.

The gap is widening because of the changes overtaking the economy and the labor market. Employment is dropping among the big corporations that routinely provide extensive health benefits to their employees. The total number of jobs throughout the country has been rising, but the greatest growth is in the kinds of work, and the kinds of companies, in which health insurance is meager or nonexistent. More than half of the people with jobs but no insurance are in retailing or the service industries. To count it another way, most are either self-employed or in firms with fewer than 25 employes. Since the shift of jobs into these categories is going to continue, it seems very likely that the insurance gap will keep growing.

Mortality rates are higher among people without insurance, particularly infant mortality rates. People without insurance tend to wait too long to get medical help. When they do seek help, the cost is likely to fall on the hospitals whose bills they can't pay -- and ultimately on other patients and their insurance.

Most industrial countries have universal health insurance and regard it as a basic social necessity. The United States has never adopted universal coverage on grounds that it would cost more than the country can afford. Several days ago this paper published descriptions of the universal systems in Canada, France and Japan. In all three countries, spending on health and medical care is substantially lower, per person, than here in the United States. But health care is, in general, as good. Mortality rates are as low in Canada as here, and in both Japan and France they are slightly lower.

Life expectancy is not the only measure of the quality of medical care, but neither is it irrelevant as an indicator of the kind of care that most people get most of the time. At its best, inmany specialties, American medicine is unparalleled. But a national care system that leaves 11 million children with no medical protection whatever is not satisfactory, least of all in a country that prides itself on its wealth and its sense of equity.