A recent cartoon shows two Indians standing at Plymouth Rock as the Mayflower sails in. One Indian says to the other, “Looks like we need to start restricting immigration.” And the restrictionists have been keeping up that drumbeat ever since.

Last week the Immigration and Naturalization Service announced that the United States accepted 910,000 new immigrants in 1996, an increase of about 25 percent from 1995. Antiimmigrant groups, such as the Federation for American Immigration Reform, seized upon the uptick as evidence of America’s porous borders. As one critic put it, the United States is being “deluged with foreign blood.”

To people like me, who believe that immigrants are generally assets to our economy and our culture, the fact that the gates of opportunity have been inched further open is good news. But even for people who favor a more restrictive policy, the new numbers are hardly cause for alarm. The INS reports that the higher numbers are temporary. After the 1996 crest, new admissions will begin to fall back to about 700,000 per year.

Dueling evaluations of immigration raise an important question: how many immigrants are too many? That question can’t be answered without knowledge of our immigration history. It is indeed true that immigration has reached high levels in the 1990s. Nearly 8 million legal immigrants will arrive on our shores in this decade, about the same number that came in the 1980s. The number is far below the 10 million who arrived through Ellis Island between 1900 and 1910, when there were far fewer Americans.

Properly measured, immigration doesn’t begin to approach the peak levels of earlier times. For example, in 1910 immigrants were arriving at a pace of about 12 per 1,000 residents. Today the rate of immigration has plummeted to about 4 per 1,000 residents. And that’s the most expressive statistic on the impact of immigrants on America. Effects on our job market; our culture; and our roads, hospitals, schools and the rest of our physical infrastructure are largely determined by the number of newcomers relative to the number of Americans already here. It is easier to assimilate 100 newcomers into a gigantic metropolis than into a small town.

Opponents of immigration opponents note that in recent decades the percentage of foreign-born Americans has been creeping upward. In 1970 only about 5 percent of Americans were born abroad. According to Census Bureau data released last week, now 9 percent of Americans are foreign born. Doesn’t that prove an immigration surge?

Again, that lacks historical context. In earlier periods of our history as many as one in six Americans was foreign born. We were more a nation of immigrants a century ago than we are today. In fact, the percentage of foreign-born Americans is lower today than it was at any time between 1850 and 1940.

Critics of immigration argue that at the turn of the century America was a young, underdeveloped nation that needed strong bodies; in the 1990s we need strong minds. But that is precisely what so many immigrants are bringing to the United States. The National Science Foundation recently reported that 40 percent of Ph.D.s in science and engineering are awarded to immigrants. The limits-to-growth crowd says that all the new frontiers in America have now been populated. They lack the vision to see the exciting new frontiers of science, technology, the Internet and space that are just beginning to be pioneered — with the help of the brain power that we import from around the globe.

Some environmentalists complain that the U.S. population may grow to 400 million people by 2050. Their goal of population stabilization (some even want negative population growth) is impeded by immigration. Yet if overpopulation is measured by the number of people per square mile, the United States is one of the most underpopulated of the industrialized nations. Moreover, there is no economic or environmental reason that population stabilization is preferable to a 1 or 2 or 3 percent growth rate. In fact, most recent economic research has dismissed the argument that population growth is in any way inimical to economic growth or sound environmental policy.

Last week the Senate Immigration Committee held hearings on immigrant entrepreneurs in America. Republican Sen. Spencer Abraham of Michigan, who sponsored the hearing, noted that for too long people in Washington have neglected to “talk about the positive aspects of immigration — the means by which immigration and immigrants have contributed to America’s greatness.”

The star witness at the hearing was Ovidiu Colea, who was captured in 1958 after trying to flee from behind the iron curtain in Romania. After spending five years in a prison camp, enduring beatings and near-starvation, Colea escaped and fled to America. He later founded the acclaimed Colbar Art Inc. in New York City. “When I came to America I was penniless,” he said, “but this country gave me hope and opportunity.”

Some people look at the immigration statistics just released and gloomily protest that there will be 900,000 more mouths to feed. Senator Abraham and others think that means 900,000 more fertile and productive minds for America.