High on Congress's agenda in September is immigration. The Morrison bill in the House could do more to advance all the goals of the United States during the next decade or two than any other pending legislation. Yet the Bush administration and organized labor -- an unlikely couple -- seek to gut the bill because of economic ignorance and nativism.

Worldwide, barriers to freedom have been collapsing. Messages and ideas now penetrate everywhere electronically, cheaply. And financial capital speeds from country to country and, like Mercury, eludes governmental control.

Mobility of goods and people has increased from a walker's pace to jet speed. And political barriers to trade have diminished, despite newspaper stories about trade hassles. All these changes mean more liberty.

Yet there remain barriers to the movement of the most important of "goods" -- human beings. Against the economic and cultural welfare of individual nations, and against the interests of all civilization, countries still prevent people from going where they want to go. True, people are no longer penned up in the country in which they are born, except for in the Soviet Union, China, Albania, Vietnam and a few other countries. But without the freedom to enter where they want to go, freedom to leave is of diminished value. We still tell almost all people of talent and energy who wish to join our society, "You may not enter unless you have relatives in the United States."

What foolishness. An unassailable body of recent economic research proves that we are made richer by allowing people to enter freely. We also know from a body of indubitable historical and sociological research that migrants carry valuable ideas with them and create new ideas as a result of having lived in two cultures.

What cheats us of these benefits? Age-old "common sense," economic misunderstanding cum racism (or "nativism," in polite lingo). But sometimes there is an opportunity to drive back the forces of darkness. Now, Rep. Bruce Morrison's (D-Conn.) immigration bill, just voted out of the House Judiciary Committee, promises a bright morning for human liberty.

The main thrust of the Morrison bill is an increase in the number of persons who will be allowed to enter the United States. Keep your eyes focused upon the crucial overall number, and the attempt of the anti-immigration lobby and Sen. Alan Simpson (R-Wyo.) to put a "cap" on immigration. The total matters more than how the overall number will be divided among family reconstitution, skill-based immigration, a point system, this country or that one, etc.

Here are the key demographic and economic facts:

Immigrants do not cause native unemployment, even among low-paid and minority groups. Recent studies all agree that the bogey of "displacement" of natives does not exist. New entrants not only take jobs, they make jobs with their purchasing power and with the new businesses they start.

Immigrants do not rip off natives by over-using welfare services. Immigrants typically arrive when they are young and healthy. Hence new immigrant families use less welfare services than do native families, because immigrants do not receive expensive Social Security and other aid to the aged. And immigrant families pay more taxes than do native families. Therefore, an average immigrant family puts about $2,500 into the public coffers every year -- enabling a native breadwinner to retire two years earlier than otherwise.

Immigrants bring high-tech skills that the economy needs badly. Immigrants are not "huddled masses." The proportion of new arrivals with post-graduate education is far higher than the average of the native labor force.

Immigration is low rather than high relative to historical rates of immigration in the peak years at the turn of the century. Immigration as a proportion of population is less than a fourth of what it was earlier. Even in absolute numbers, total immigration is nowhere near its volume a century ago.

The foreign-born population is only about 6 percent now -- less than the proportion in such countries as Great Britain, France and Germany, vastly lower than in Australia and Canada and less than half of what it used to be here.

Natural resources and the environment are not at risk from immigration. The long-term trends reveal that our air and water are getting cleaner rather than dirtier, and our supplies of natural resources are becoming more available rather than exhausted, contrary to common belief. Immigration increases the technical knowledge that speeds these benign trends.

Immigration reduces the social costs of the elderly, which can't be cut. More and more of the U.S. population is retired, with a smaller proportion of adults in the labor force. New immigrants typically are just entering the prime of their work lives and tax-paying years. Immigration is the only feasible way to lighten the Social Security burden of the aging U.S. population. It also reduces the federal deficit, which would not exist if people still lived the short lives and had the large numbers of children that they did early in this century.

The writer teaches business administration at the University of Maryland.