This Earth Day, the biggest challenge to environmentalists is not global warming, nor potential drilling in wildlife refuges, nor disappearing rainforests. The news environmentalists really should be riled up about came not from the Environmental Protection Agency but from the Census Bureau: the United States’ record population growth, which is on a collision course with our environmental goals.

The news that the U.S. grew by 13 percent in the last decade—higher than anyone’s projections—spells disaster for just about any environmental issue you can name. More people means more demands for resources, more pollution, and more waste. More people means more energy use, escalating global warming and energy shortages. More land is required for agriculture, causing deforestation and soil erosion. More homes, factories, and roads must be built, destroying habitat for other species.

Population growth is particularly significant in the affluent U.S., where even the environmentally conscious have levels of consumption far exceeding the rest of the world. Every year, America paves over an area equal to the entire state of Delaware to meet the needs of more people. More than half of our original wetlands are now gone forever. We produce 222 million tons of trash each year—4.4 pounds per person each day—more than half of which ends up in landfills. And each new American uses 175 gallons of water per day and 26 barrels of oil per year. In fact, with five percent of the world’s population, Americans use 25 percent of the world’s resources.

Plainly put, American population growth is far worse for the planet than population growth anywhere else. And unless we reduce population, we won’t reach any of our environmental goals. Our best efforts to conserve water and energy, reduce pollution, control sprawl, and preserve green spaces will continue to be overwhelmed by population growth.

In poll after poll, Americans from Sarasota to Seattle side with ecologists who conclude we already have too many people. And both the Rockefeller Commission on Population and the American Future in 1972 and the President’s Commission on Sustainable Development in 1995 urged that the U.S. adopt policies to stabilize the U.S.’s population. But Congress never acted, and instead we have grown from 200 million to 283 million.

Where is the growth coming from? At the first Earth Day in 1970, nearly all U.S. population growth was caused by births to American-born women. In the mid-1970s, our native-born fertility rate dropped to replacement level (an average of two children per woman, the number necessary to replace the mother and father), where it has remained. In the long run, this level would have resulted in a stable and more sustainable U.S. population size. But it didn’t, because even as our fertility rates were stabilizing, the number of new Americans kept increasing.

Immigration levels, once a few hundred thousand annually, began rising a few decades ago and today are five times our traditional average—over one million every year. No surprise, then, that instead of seeing our population level off as our fertility stabilized, the U.S. experienced a record 13 percent population increase of 35 million people in the last decade—a staggering 87 percent increase in the last 50 years.

And we’re not done yet. The Census Bureau projects that we will swell to 400 million by 2050, with most of the increase due to immigration. How will we house, educate, and feed an additional 117 million people without causing irreversible damage to our environment?

America is overpopulated. Despite our best intentions, we can no longer afford to absorb the excess population of other countries. Instead, we should set sensible, lower limits on immigration and work to improve living conditions in the third world, helping them become places people aren’t driven to leave.

This Earth Day, let’s begin a national discussion about where our never-ending population growth is taking us—colossal soil and forest destruction, plant and animal extinction, air and water pollution (not to mention traffic congestion, overcrowded schools, and ever-increasing sprawl)—and whether that’s the future we want. Out-of-control population growth doesn’t need to be our destiny.