The massive flow of immigrants to the United States in recent years has had little impact on the nation's job market except in a few key states, according to a two-year study commissioned by the Ford Foundation.

The study, conducted by the National Bureau of Economic Research, showed that despite the large flow of immigrants -- legal and illegal -- since the 1970s, the immigrant share of the nation's labor force remains small.

"The modest increase in the immigrant share of the work force . . . may surprise those familiar with the more dramatic increase in the ratio of immigrants to population," said Richard Freeman, a Harvard economist who coordinated the study.

Although the study showed that immigration had little adverse impact on the job market nationally, it acknowledged that increased immigration had created some regional problems. According to the study, more than half of all immigrants since 1980 have settled in four states -- California, New York, Texas and Florida.

In these areas, the study showed a significant impact on jobs. The situation is further aggravated by the apparent immobility of the immigrants. "Immigrants arrive in the United States in a number of gateway cities and, for the most part, stay there," Freeman said.

George Borjas, an economist from the University of California at Santa Barbara, said the flow of immigrants to the United States has been steadily increasing since the 1950s.

"In the 1950s," he said, "the flow of legal immigrants averaged about 252,000 a year. By the 1970s, the average annual flow had increased to 449,000 persons, and by the early 1980s, the average annual flow was over 570,000 persons." In addition, he said, approximately 2 million Mexicans were living illegally in the United States in 1980, the time of the last census.

The study concluded that "immigrants have been absorbed into the American labor market with little adverse impact on natives." It showed that the greatest job impact typically was felt by other immigrants. "Increased immigration has some modest adverse impacts on the employment and wages of workers who are the closest substitutes for immigrants, the immigrants themselves and earlier immigrants, but little if any impact on young black and Hispanic-Americans, who are likely to be the next closest substitutes," Freeman said.

He said the study showed that employment and wages of less-educated black and white native-born Americans have not worsened noticeably in cities where the immigrant population rose in the 1970s.

"There is little in this research to indicate that redistributive effects of immigration should be a major policy concern," said Robert Topel, a University of Chicago economist who assisted with the study.

But Harvard economist John Dunlop, who served as secretary of labor in the Ford administration, cautioned the economists that government policymakers concerned about the regional effects of immigration on job markets will not be overly influenced by the study because they will attempt to develop policies to deal with regional employment problems.

"I do feel that . . . you're not going to persuade anybody in the policy business," he said, urging the economists to focus next on regional problems of immigration and jobs.

Freeman cited two reasons why immigrants did not take a greater share of U.S. jobs. First, he noted the increased "native labor supply" resulting from the Baby Boom generation reaching working age and the increased participation of women in the work force.

But just as important, he said, was the fact that "immigrants do not have an especially high labor force participation rate." Freeman said the study showed that unlike some immigration patterns of the past, many of today's immigrants come to the United States to unify their families, not necessarily for economic opportunity.

Freeman said the dramatic change in recent decades is in the composition of immigrants. "Since the 1964 immigration law, an increasing proportion of immigrants have come from Asia and Latin America, many with less labor

market skills than earlier post-World War II immigrants," Freeman said.

The study showed that from 1959 to 1971 nearly 40 percent of all immigrants to the United States came from Europe. In the period from 1971 to 1981, the percentage dropped to 17 percent, while immigration from Asia rose to more than 37 percent.