Nearly 10 million Americans lost their jobs due to plant closings or layoffs from 1983 to 1988 despite the longest peacetime economic expansion in the nation's history, the government reports.

Of 9.7 million displaced workers during the period, 4.7 million were so-called tenured workers who had held their jobs for three years or more, the Bureau of Labor Statistics says in the latest of its biennial reports on worker displacement.That was a slight decline from earlier BLS studies of overlapping five-year periods - 1979-84 and 1981-86 - which both had shown that 5.1 million tenured workers lost their jobs during the respective periods. But each of those periods also included the severe recession of 1981-82.

As a result, government and private economists say the new figures show a persisting displacement problem.

Larry Mishel, an economist for the Economic Policy Institute, a liberal Washington think tank, called the decline in job displacement after the recession years "surprisingly small."

The BLS began conducting the displacement surveys in 1984 at the request of the Labor Department's Employment and Training Administration. The latest report was released over the weekend.

While the 1984 and 1986 surveys showed 50 percent of the displaced workers coming out of factories, only 40 percent of the tenured workers losing their jobs in 1983-88 had been employed in manufacturing.

In conjunction, the distribution of the layoffs has shifted somewhat from blue-collar occupations such as machine operators, laborers and repairmen during the recession periods to white-collar management and sales occupations from 1983 to 1988.

"This was the lean-and-mean era, when companies went after middle-level managers and other white-collar workers," said Mishel. "But a lot of it, especially in retail trade, is also somewhat related to these leveraged buyouts. It's probably the better-paid retail workers who lost their jobs."

One thing that hasn't changed is the percentage of workers who were given some kind of advance notice before losing their jobs. In all three surveys, roughly six of every 10 displaced workers had been told in advance to "expect a layoff."

But only two of every 10 in the latest survey said they had received a written notice of their impending dismissals - a trend bound to change in view of a new law requiring 60 days written notice of plant closings and large layoffs beginning in 1989.

Of the 4.7 million tenured workers who lost their jobs from 1983 to the end of 1987, 71 percent or approximately 3.2 million of them had new jobs as of January last year.