By Tom McCarthy/New York

The US population was expected to grow just 0.7% in 2013, to arrive at 317,297,938 people on New Year’s Day 2014. That rate was down from 0.73% in 2010-2011 and much lower than the 1.2% growth rate of the 1990s, a decade of economic expansion.

The US has not seen such slow growth since the Depression era of 1933-1937, according to William Frey, a demographics expert and senior fellow at the Brookings Institution.

“Up until 2008, really we didn’t see those growth rates change much,’’ Frey said. “This sharp bump that we’ve seen in the last few years does suggest that the economy has a lot to do with it.’’ But average annual growth, Frey said, is a “fairly crude measure’’ that can miss the underlying influence of immigration laws and changing cultural and social mores.

“In the Great Depression era, migration laws were stricter in the late teens and early to mid-20s,’’ he said. “You had lower fertility rates as well, with the very dire circumstances’’ of many families.

From 1932-1933, population growth settled at 0.59%, creeping to 0.60% in 1937, according to census bureau figures.

Declining unemployment and other recent signs of economic life have yet to register on the population scales. Real GDP growth picked up in 2011 after declining sharply in the first decade of the new millennium, from nearly 1% a year in 2000 to just more than 0.3% in 2010.

Regional population trends show more people appearing in the south and west, and fewer appearing in the Midwest and Northeast, a continuation of long-term patterns. The south was estimated to host 37.4% of the population in July 2013, up from 35.6% in 2000. The north-east’s share was estimated to have shrunk to 17.7%, from 19.0% in 2000.

In a developing demographics horse race, Florida appears poised to overtake New York in the near future as the third-most-populous state. The Sunshine State, currently fourth, grew 2.7% between April 2010 and July 2012, while the Empire State grew only 1.0%. The national average for the period was 1.7%. Far out front for head count was California, with an estimated 38.3mn residents by July 2013, the latest available figures. Texas was No 2 with 26.4mn.

The state charting the most growth was North Dakota, which jumped 7.6% from 2010-2013. The discovery in 2008 of untapped oil and gas reserves in the state has attracted so many new arrivals that longtime residents of towns fueled by the boom are moving out to make room.

The census bureau estimates that there is one birth on average in the US every eight seconds, and one death every 12 seconds. And with one international migrant added every 40 seconds, the country gains one person about every 15 seconds.