New US Population: 313.9M That's up less than 1% as growth remains flat By John Johnson, Newser Staff Posted Dec 20, 2012 1:11 PM CST 13 comments Comments (Shutterstock) (Newser) – The US Census Bureau now pegs the US population at 313.9 million people, up a scant 2.3 million, or .075%, from last year, reports USA Today. Small as it is, the increase actually reverses five years of slowing growth, notes the AP, though we're still at a level that hasn't been seen since the Great Depression. Birth rates and immigration remain in decline. Also: An oil boom in North Dakota made it the fastest-growing state in terms of percentage, up 2.2%. Next came DC, Texas, Wyoming, and Utah. Texas gained the biggest number of people, 427,400. Rhode Island and Vermont were the only states to lose population. California remains the most populous state with 38 million residents. In Maine and West Virginia, aging populations mean that deaths now outnumber births. Florida posted a net gain of 200,000 people, a rebound from its recent trend of having more people leaving than moving in.