A nation facing its future: population growth threatens freedom.

As individuals and as a nation, we're defined by the choices we make. And too often, by the tough decisions we avoid. Most of us have avoided even thinking about how our rapidly growing population is affecting our quality of life and shaping our society.

Our population has more than doubled since World War II, and at this rate, we could be on our way to 1 billion people living in the United States by the end of the century.

Our population growth, driven in part by unchecked immigration, is already straining our health care and educational systems and, less noticeably but far more important, putting a heavy burden on our land, food production, water supply and the quality of the air we breathe.

All these pressures on our resources will only worsen unless our leaders begin a national dialogue on the future of this country and start making the tough choices. Our future will be shaped largely by our trade policies, our environmental and economic policies and our immigration policies.

Democrats and Republicans, liberals and conservatives, are avoiding debate on these issues because they are the most difficult ones for politicians to confront. In campaign parlance, these are wedge issues. But failure to come to terms with them will drive a wedge between all of us and a prosperous, healthy future for this country.

The U.S. population is growing by more than 3 million each year. Food and agriculture generate $40 billion a year in export income for the United States, but at the present rate, we won't be exporting food at all by 2025.

Our water supply is equally at risk. "We're overpumping and overusing our water," says David Pimentel, professor of ecology and agricultural sciences at Cornell University. If left unaddressed, droughts could become a way of life in many states.

Our air quality is not improving, either. Despite legislation and industry regulation, nearly half of this country lives in counties with dirty air. It is estimated that as many as 50,000 people go to hospitals each year because of air pollution. And environmental regulators say that the smog in Los Angeles is the worst it has been in seven years.

Schools in many cities are severely overcrowded. California is facing nothing less than a facilities crisis. There are about 6 million students in mostly overcrowded California public schools. Of that total, about a quarter, or 1.5 million, are students whose primary language is not English.

Funding for California students with limited English has tripled since 1986. Federal grants for special language programs have more than doubled from $157 million in 1995 to $460 million in 2002.

The strains of overcrowding are equally apparent in our health care system. Hundreds of emergency rooms have closed over the past decade because of budget shortfalls, and the ones that remain open are overburdened. Hospitals also are writing off as much as $2 billion a year in unpaid medical bills to treat illegal aliens, who are ineligible for Medicaid.

Our population explosion not only detracts from our quality of fife but threatens our liberties and freedom as well. As Pimentel puts it, "Back when we had, say, 100 million people in the U.S., when I voted, I was one of 100 million people. Today, I am one of 285 million people, so my vote and impact decreases with the increase in the population." He adds, "So our freedoms also go down the drain."

In order to even begin coping with our overpopulation crisis, we must first understand that it is often a determining factor in other critical areas: our schools, hospitals, infrastructure, economy and our very way of life. We must prepare to make very tough choices on all these issues that we've too long ignored.

Lou Dobbs is the anchor and managing editor of CNN' s "Lou Dobbs Tonight."