THE AMERICAN population was shifting toward the South and West in the 1970s, as the census figures demonstrate. But another basic pattern, the national distribution of income, was also rapidly changing -- and not always in the same directions. The federal Bureau of Economic Analysis tracks the country's economic geography, and, since the population movements are currently getting the customary decennial attention, it's not a bad idea also to see where the money went.

Throughout most of this century, wealth migrated to the two coasts -- to the Middle Atlantic states and to California. But in the 1970s, that trend was abruptly reversed by the world shortages of oil and food. Suddenly it was the oil, coal and grain states in which incomes were rising disproportionately rapidly. Nearly all of them, historically, had been poor states. If you look up the rates at which average personal incomes rose in the decade of the 1970s, you will find the fastest advances were in Wyoming, North Dakota and Oklahoma.

In the North, there has been immense anxiety over the census's evidence of a steady flow of people southward. But wealth does not necessarily follow population. Many of the people moving South have been either young or retired, and few have taken large incomes with them. The really dramatic rises in personal income in recent years have followed the drilling rigs and the harvesters. The Sun Belt's prosperity has risen, true enough. But in the 1970s personal incomes rose a good deal faster in Kansas and West Virginia than they did in Arizona, Florida or Georgia.

The regional effects of the oil and grain revolutions have been remarkable. Texas, historically a low-income state, had an average as recently as 1969 that was fully one-tenth below the national average -- a large disparity by American standards. In rich Massachusetts that year, the average income was one-tenth above the national figure. But by 1979, average incomes in the two states were almost exactly the same and both were almost exactly at the national average. At least in regional terms, the economic upheavals of the past decade have had the effect of equalizing incomes.

New York has suffered a particularly harsh decline in its relative standing among the states. For years it had ranked among the top several. But in 1979 the average income there was lower than in a dozen other states, including some not usually considered remarkably rich -- Illinois, Maryland, Kansas. Incomes in New York rose far less rapidly during the decade than in any other state. That helps explain the extraordinary financial distress of both the state and its largest city. The case of New York indicates the scale of the strains generated by these sharp and unanticipated changes in the geography of wealth. Wherever state and local governments ignore these changes, similar misfortunes lie ahead.