WASHINGTON (AP) – Orders to American factories surged in March by the largest amount in a year, an encouraging sign that the recent slowdown in manufacturing may be ending.

The Commerce Department said Wednesday that total factory orders rose by 3.1 percent in March, pushed higher by a big jump in demand for commercial aircraft and the biggest rise in the category that tracks business investment in new equipment in 2 1/2 years.

The increase was far better than the 2 percent figure that analysts had been expecting and offered hope that manufacturers were beginning to experience rising demand after a recent weak period brought on by troubles in housing and auto sales.

The good news on factory orders followed a report from the Institute for Supply Management that its closely watched gauge of manufacturing activity rose to 54.7 in April, the best showing in 11 months.

The index had dipped below 50 in November and January, indicating the manufacturing sector was contracting, as companies trimmed inventories to cope with the serious slump in housing and an overhang of unsold autos.

The improving data has prompted some economists to say that the worst of the manufacturing slump may be ending.

For March, the government said that orders for big-ticket durable goods rose by 3.7 percent, even better than a preliminary report last week which had put the increase at 3.4 percent.

Orders for nondurable goods, items like petroleum and chemicals, rose by 2.3 percent, the biggest gain since January 2006.