Revised data released Wednesday also suggest a possible factor behind the pickup: Americans saved much more in 2012 than previously thought, leaving more to spend in 2013.
The economy grew at an annual rate of 4.5 per cent in last year's third quarter, up from a previous estimate of 4.1 per cent. Growth was 3.5 per cent in the fourth quarter, up from 2.6 per cent. The average 4 per cent annual pace was the best six-month showing since 2003.
For 2013 as a whole, the economy expanded 2.2 per cent, up from the previous estimate of 1.9 per cent.
The government's newly revised figures show that growth was accelerating before harsh weather in the first quarter contributed to a sharp contraction. And growth rebounded to a robust 4 per cent annual rate in the April-June quarter, the government said Wednesday. The figures indicate that the 2.1 per cent contraction in the first quarter was an aberration. That number was revised higher from a previous reading of a 2.9 per cent contraction.
The better growth readings also suggest that this year's healthy hiring trend will continue. Previously, the job gains in the first six months of this year were much stronger than the economic growth figures. Now they are more closely aligned.
Still, growth was weaker in 2011 and 2012 than the government had previously estimated, the revisions show. Overall, the growth trend since the Great Recession was little changed by the government's updates. The new figures show that growth has averaged 2.3 per cent at an annual rate from the end of the recession in June 2009 through last year. That's a scant downgrade from the previous estimate of 2.4 per cent.
The economy expanded just 2.3 per cent in 2012, down from a previous estimate of 2.8 per cent. And growth in 2011 was marked down to 1.6 per cent from 1.8 per cent.
The changes stem from a comprehensive revision the government conducts each year to the nation's gross domestic product data. GDP, the broadest measure of the economy's output of goods and services, includes everything from restaurant meals to television production to steel manufacturing. Most of the changes were made to the previous three years' figures.
The revisions are based on updated data from agencies such as the Census Bureau and the Internal Revenue Service. Many monthly surveys of consumer spending, manufacturing and retail businesses are updated with more comprehensive annual reports.
Newly available tax data showed that Americans earned more than was previously thought in 2012. Personal income, after taxes and adjusted for inflation, grew 3 per cent that year, much higher than the previous estimate of 2 per cent.
But the bulk of that gain likely went to wealthier Americans. Most of the upward revision resulted from a sharp increase in interest and dividend payments. Business income was also revised higher. Wealthier Americans own the vast majority of stocks and other financial assets.
The higher interest and dividend payments probably included many one-time payments that were made ahead of tax increases that kicked in at the beginning of 2013.
With income much higher, so was savings. The saving rate was revised to 7.2 per cent in 2012, up from the previous estimate of 5.6 per cent. Americans also saved more in 2011 and 2013. Though more savings can slow growth in the short run, it can lay a foundation for faster growth in the future.