The number of cars and trucks in the country rose by 2.2 million annually in the decade of the 1950s and by 3.7 million a year in the 1960s. In the current decade it is rising by 4.4 million a year - or five times as fast as the population.

The auto explosion expressed in those figures - which I have taken from Anthony Downs of the Brookings Institution - represents perhaps the dominant social event in the country. It explains why it has been so hard to frame an energy program, to clear up traffic, polluted air and court dockets and - most important of all - to do anything about the inner cities and their down-and-out populations.

The auto is probably the foremost example of a technological innovation that developed, as it spread, vast and largely unforeseen social consequences. It began as a kind of toy, and then became an enormous convenience. But as the numbers rose, problems came.

Immediately there was the matter of traffic congestion. Congestion of the air by auto fumes, though first denied by the car companies, was later proved by scientists in California.

Court dockets became so crowded with accident cases that about a decade ago relief was sought through no-fault insurance. The oil shortage of 1973 and the growing dependence on foreign sources for oil highlighted the role of the auto as a consumer of an increasingly scarce natural resource.

Probably the least well-perceived consequence of the auto is its impact on the center cites. But basically it is the car that makes possible suburban living and the relocation of industry to the fringes of town. More and more of the white middle class moves to the suburbs, and the cities become increasingly dominated by the black and brown minorities. More and more industry also moves to the suburbs, leaving fewer and fewer jobs available downtown.

Thus there is set in motion the downward spiral that has overtaken most central cities in the North and the Midwest and is beginning to be felt in the South and West as well. As the local population declines in education and income, expenses for schools, welfare and crime go up. But the tax base goes down and the cities are plunged intocrisis - a crisis inextricably linked with the rise of the car and the growth of the suburbs.

Against the background and the soaring cost of cars, the continued love of the American people with the auto culture shows the workings of the basic force. Not only are more and more cars and trucks on the road all the time, but the rate of growth is rising as well.

Moreover, the coming decline in population does not augur any falling-off in purchase of cars and trucks. The number of households owning no cars grew hardly at all between 1955 and 1975. There was only a slight increase in the number of families owning one car. The big bulge came in families owning two vehicles. So there is plenty of space for more purchases of cars and trucks.

What all this says to me is that the disposition of Americans to keep buying cars and trucks has to be taken as a basic fact of life. Not only are millions and millions of individuals dependent upon their cars, but furthermore the country's major industries are all bound up with autos. If anything, it is clear that the United States is not soon going to kick the car habit.

Once that fact is accepted, there inevitably follow certain guidelines for dealing with the social problems connected with autos. Tight emission standards are increasingly important in cleaning up the air as is no-fault insurance in easing court dockets. Except in a few cities, mass transit does not look like a good bet.

Probably the most agonizing difficulty is that of the center cities. The auto explosion means to me that the suburbs will continue to grow as the site of both housing and business. There will be steadily fewer jobs available in the center cities, and the notion of an urban renaissance seems to me a case of trying to spit against the wind.

My feeling is that the best hope lies in a defensive struggle that will preserve in the cities those assets that cannot be moved while easing for other activities and residents the adjustment to the predominantly suburban future. What is wanted, in other words, is not the phony promise of renewal but a Fabian strategy that will control damage over a long period of time.