During the passionate arguments this summer about immigration and whether or not amnesty should be granted to illegal aliens, one subject was lost in the din. Few mentioned the impact that immigration has on America's population.

Proponents of more immigration claim that businesses, workers and consumers benefit. Those opposed counter that mass immigration creates sprawl, congestion and a diminished quality of life.

But whichever camp you align yourself with both sides agree with the obvious—that more immigration means a larger population.

The non-partisan Washington, D.C.-based Center for Immigration Studies, a think tank focusing exclusively on immigration's impact on the U.S., has issued a new report by Dr. Steven Camarota titled 100 Million More: Projecting the Impact of Immigration on the U.S. Population, 2007-2060.

Listen to Camarota discuss his report on PHXNews here.

Using Census Bureau data as its source, the report found that:

• Currently, 1.6 million legal and illegal immigrants settle in the country annually; 350,000 immigrants leave each year, resulting in net immigration of 1.25 million.

• If immigration continues at current levels, the nation's population will increase from 301 million today to 468 million in 2060—a 167 million (56 percent) increase. Immigrants plus their descendents will account for 105 million (63 percent) of the increase.

• The total projected growth of 167 million is equal to the combined populations of Great Britain, France, and Spain. The 105 million from immigration by itself is equal to 13 additional New York Cities. Or the current population of Mexico

But if the annual level of net immigration were reduced to 300,000, future immigration would add 25 million people to the population by 2060, 80 million fewer than the current immigration level adds.

However, since net immigration has been increasing for five decades, only an immediate and sharp decrease would significantly affect population levels.

Some analysts predict that continued high levels of immigration will revitalize what they say is an aging population base.

But in an interview with Dr. Camarota, he told me that immigration has only a small effect on slowing the aging of American society.

As detailed in the report, if the current level of net immigration is sustained (1.25 million a year), 61 percent of the nation's population will be of working age (15-66) in 2060, compared to 60 percent if net immigration were reduced to 300,000 a year.

 And if net immigration were doubled to 2.5 million a year it would raise the working-age share of the population by one additional percentage point, to 62 percent, by 2060. But at that level of immigration, the U.S. population would reach 573 million, double its size in the 2000 Census.

The report's finding are based on the Census Bureau's middle range assumptions about future birth and death rates, including a decline in the birth rate for Hispanics, who comprise the largest share of immigrants.

What gets lost in the immigration debate is that if immigrants come to America for a better life, which they obviously do, in the process they become consumers of social services, cars and parking spaces, hospital beds, water and classroom seats.

When population increases, America's ecological footprint—the human demand on nature's resources—is negatively impacted.

The enormous population increases projected by the CIS report have different implications depending on where you live. If you reside in the already overcrowded urban areas of Los Angeles or San Francisco, little land is available for more building.

But if you live in the San Joaquin Valley, then vast amounts of agricultural land would be lost as more homes are built for the expanded populace. Lodi's population, based on the report, will increase from today's 60,000 to 94,000

Sustainable growth is a vitally important goal that should be included in any discussion about immigration.

Of the four variables that effect population growth—immigration, migration, births and deaths—only immigration can be controlled, assuming a vigorous federal policy existed to limit the numbers of people arriving.

Politicians find discussions about immigration restriction distasteful. But if manageable growth is a goal, sensible immigration policies must be developed and followed.

Joe Guzzardi [email him], an instructor in English at the Lodi Adult School, has been writing a weekly column since 1988. It currently appears in the Lodi News-Sentinel.