AMERICAN immigration, already running at near-record levels, now is expected to set an all-time high during the 1990s. A new study by Leon Bouvier of Tulane University projects migration to the United States will reach 9 million to 12 million in this decade. The highest level in any decade, 8,795,386, came between 1901 and 1910.The immigration issue exploded into public view again this week over a controversy involving 2,160 Haitian boat people who were picked up on the high seas by US Coast Guard ships. The Haitians are fleeing their homeland for the US in small boats. The White House this week returned hundreds of them to Haiti, while arranging for others to be settled in Venezuela, Honduras, Belize, and Trinidad and Tobago. Only 53 were deemed potentially eligible for US asylum. The decision on the Haitians, who are black, drew criticism on Capitol Hill. "A racist and vicious policy," charged US Rep. Charles Rangel (D) of New York. Sen. Connie Mack (R) of Florida called Bush's action "the worst scenario." He observed: "We've been a beacon of freedom for two centuries and now we're being selective about who we're offering that opportunity to." Dr. Bouvier says such pressures from Congress, and sky-high birthrates abroad, almost certainly will lead to greater levels of immigration in this decade. The greatest impact will be in California, which is already struggling to feed, house, and educate a large and growing population of immigrants. The Los Angeles area alone is expected to receive at least 2 million new settlers from other countries in the 1990s. California officials worry that rising social costs caused by immigration will drive hundreds of businesses out of the state. Rapidly growing numbers of immigrants are expected to settle also in New York, Texas, Florida, Illinois, and New Jersey. If these trends continue, immigration will also have a historic impact on US demographics. California will no longer have a majority white population by 2000, and in New York and Texas, whites will lose their majority status by 2020. According to Bouvier's estimates, if immigration rates remain high the entire US will no longer have a white majority by 2050 or 2060. Several factors inside and outside the United States are drawing millions of people to this country. In Europe, communism's collapse has let hundreds of thousands of people seek better lives in Israel, the US, and Germany. In Latin America, Asia, and Africa, booming populations are putting pressure on young people without jobs to flee to Europe and the US. Mexican workers, for example, can often boost their incomes ten-fold across the border. Inside the US, several factors are encouraging greater immigration. In 1990, Congress broadened immigration rules. In the late 1980s, about 700,000 persons legally entered the US each year. The new laws will boost that to approximately 900,000, according to a study by the US General Accounting Office. A 1986 law granted amnesty to 3 million persons who were illegally residing in the US. These people will be permitted to bring in their parents and children toward the end of the 1990s. A third factor cited by Bouvier is the growing number of refugees around the world. For example, with Hong Kong scheduled to fall under Chinese control in 1997, hundreds of thousands of Hong Kong citizens may be requesting asylum here. Finally, illegal immigration, which declined briefly after the 1986 law was passed, now is moving upward again. As population pressures mount in Latin America, illegal immigration could again go out of control. Given these factors, Bouvier says he expects the final numbers to reach at least 10 million. Rose Hanes, executive director of Population-Environment Balance, suggests that even Bouvier's record projections may be too modest. She points out that Bouvier's study assumes there is "regular migration" throughout the 1990s, without any unexpected increases. However, a new Mariel-type boat lift, with tens of thousands fleeing Cuba, Haiti, or other countries, "could dramatically increase the numbers," she says. Ms. Hanes says immigration could also rise if Congress repeals employer sanctions, which now make it harder for illegal immigrants to get jobs in the US. Several members of Congress have called for repeal. The impact of all this has begun to hit state and local governments. Gov. Pete Wilson (R) of California recently has complained of a "taxpayer squeeze" being caused in part by a surge in foreign immigration.