U.S. manufacturing output jumped last month on big gains in production of autos, machinery

U.S. factories boosted output last month, while December ended up being their best month of growth in five years.

Strong auto sales and growing business investment in machinery and other equipment are keeping factories busy and helping the economy grow.

The Federal Reserve said that manufacturing production increased 0.7 percent in January. And output soared 1.5 percent in December, according to an upward revision. That was the biggest gain since December 2006.

Overall industrial production, which includes output by mines and utilities as well as factories, was unchanged in January. The flat reading was mostly because Americans are using less energy to heat their homes during the unseasonably warm winter.

Factory output has risen 16.7 percent from its low point during the recession, in June 2009. It is still 7.1 percent below its December 2007 peak.

Jonathan Basile, an economist at Credit Suisse, said December and January marked the best two months of growth for manufacturing since the summer of 2009, when the recession ended.

“The manufacturing sector is on a tear,” Paul Ashworth, an economist at Capital Economics, said in a note to clients.

Auto production rose 6.8 percent in January, the biggest gain since July 2010, according to the Fed report. Car sales rose by the most in more than two years in January, after posting healthy sales gains in November and December.

Industrial machinery production increased 2.2 percent, after an even larger gain in December. Computer and electronics production moved up 1.4 percent.

Two strong months of manufacturing growth are among other encouraging signs that show the U.S. economy could grow at a steady pace this year. Five straight months of solid job growth has lowered the unemployment rate to 8.3 percent, the lowest level in nearly three years.

Several factors could weigh on growth this year. Gas prices are rising again. Europe’s financial turmoil could weaken demand for U.S. exports. And another year of weak pay increases could force consumers to cut back on spending.

Still, the economy is growing and manufacturing is accelerating. That has helped drive the slow but steady recovery.

Manufacturing companies have strongly boosted their efficiency in recent years, automating many plants and processes. That’s allowed them to produce more with fewer workers.

Still, many are hiring. The government said factories added a net 50,000 workers in January, the most in a year. And manufacturers added a net 235,000 jobs in 2011, the biggest annual rise since 1997.

Another positive sign: the average workweek for manufacturing employees increased last month.