The bureau said the population grew by 2.8 million or 0.92 percent between April 1, 2010, and July 1, 2011, to 311.6 million.
The estimates are the first since the Census.
The District of Columbia's population grew by 2.7 percent, faster than any of the states and its highest growth since the early 1940s when World War II drew thousands of new government employees to the capital. The five fastest-growing states were Texas at 2.1 percent, Utah at 1.9 percent, Alaska with 1.8 percent, and Colorado and North Dakota with 1.7 percent.
Three states lost population. The number of Rhode Islanders fell by 0.12 percent, while there were 0.08 percent fewer in Michigan and 0.01 percent in Maine.
While California remains the most populous state, with 37.7 million people, Texas gained 529,000, the largest absolute increase in any state. California picked up 438,000 people, Florida 256,000, Georgia 128,000 and North Carolina 121,000.
The collapse of the housing boom made for some big changes. Nevada, the fastest-growing state, dropped to 27th in the 15-month period, with population up only 0.08 percent.