Whether you see it as good news or bad news, the nation has now hit the 300 million mark.

The United States hit the population milestone at about 5:46 this morning, according to U.S. Census Bureau estimates. The nation's population clock, online at www.census.gov, was at 299,995,920 at 5 p.m. Monday.

"It's something worth celebrating," said Dan Griswold, director of the Center for Trade Policy Studies at the Cato Institute. "We're a unique nation. We have a large population and a high standard of living. That magnifies our influence."

The census estimate is based on the nation adding one person every 11 seconds. And Utah, which surpassed 2.5 million people for the first time last year, is adding one person every seven minutes, according to the Utah Population Estimates Committee.

Gov. Jon Huntsman Jr.'s office issued a statement lauding the state's continuing growth, and the nation's, saying "300 million Americans is a historic achievement for our country."

The United States is the world's third-largest nation, populationwise, behind China's estimated 1.3 billion people and India's 1.2 billion.

The nation's growth of about 1 percent a year is raising sustainability concerns among some who say we are depleting our resources. The Center for Environment and Population estimates that Americans account for only about 5 percent of the world's population but use 25 percent of its resources.

"We need to make dramatic changes," said Jim Baird, Sustainability Education Program director of the Izaak Walton League of America. "Look at the night sky over us and how many lights there are. We are using it in ways that is harming the land and its ability to rejuvenate."

Griswold, however, pointed to problems faced by nations, including Japan, Russia and much of western Europe, which are "about to see a steep population decline." That, he said, is leading to problems such as how to pay for pension programs or maintain vibrant economies.

"Our population continues to grow in part because we are a hopeful, youthful, optimistic nation," he said.

He noted advantages such as a bigger market for American companies, a more dynamic division of labor, and more innovation. He noted that Americans won four of the six 2006 Nobel Prizes.

He said Americans now have a life expectancy of 77.8 years, compared to 70.5 years when the nation hit the 200 million milestone in 1967.