Yahoo! Buzz Digg Newsvine Reddit FacebookWhat's this?By Haya El Nasser, USA TODAY If the USA seems too crowded and its roads too congested now, imagine future generations: The nation's population could more than triple to 1 billion as early as 2100. That's the eye-popping projection that urban and rural planners, gathered today for their annual meeting in Las Vegas, are hearing from a land-use expert. "What do we do now to start preparing for that?" asks Arthur Nelson, co-director of the Metropolitan Institute at Virginia Tech, whose analysis projects that the USA will hit the 1 billion mark sometime between 2100 and 2120. "It's a realistic long-term challenge." The nation currently has almost 304 million people and is the world's third most populous, behind China (1.3 billion) and India (1.1 billion). China passed the 1 billion mark in the early 1980s. Nelson's projection assumes that current fertility rates remain constant but that longevity and immigration will continue to rise. Jeff Soule, director of outreach for the American Planning Association, hopes it will be provocative enough to inspire planners who anticipate development patterns and infrastructure needs to look beyond their lifetimes and localities. "We have to be more aggressive about looking out at the long term," Soule says. "It may get people thinking beyond their jurisdictions.