Businesses at the wholesale level added to their stockpiles in January and their sales jumped by the largest amount in 14 months.

Wholesale inventories rose 1.1 percent in January, the Commerce Department said Wednesday. It was the 12th gain in 13 months.

Sales at the wholesale level rose for the seventh straight month. The 3.4 percent increase was the largest gain since November 2009.

Greater sales should encourage businesses to keep restocking their shelves and drive factory production in the months ahead.

The rise in inventories in January left stockpiles at $436.9 billion. That's 13.1 percent higher than the low reached in September 2009, when companies were slashing their stockpiles to keep costs under control during the recession.

The restocking of warehouses has helped to boost production and job growth at U.S. factories. Economists believe that trend will continue in 2011.

Manufacturers have benefited from rising demand for products in the United States and overseas. The falling dollar against many major currencies has also driven export demand. A weaker dollar makes U.S. goods cheaper on foreign markets.

The January sales increase was led by a 7.8 percent surge in demand for autos,

The rise in inventories also reflected strength in autos. Those inventories increased 2.1 percent.