WASHINGTON (AP) — Orders to U.S. factories increased in January by the most in seven months, while a key category that tracks business investment plans rose by the largest amount in 19 months.

The Commerce Department says factory orders increased 1.6 percent in January after two months of declines. It was the biggest jump since June, though it was driven by demand in the volatile category of commercial aircraft. At the same time, orders in a core sector that serves as a proxy for business investment rose 3.4 percent — the sharpest one-month gain since June 2014.

U.S. manufacturers' export sales have been hurt this year by spreading economic weakness overseas and by a strong dollar, which has made their goods less competitive. And a sharp fall in oil prices has hurt investment.