U.S. factories increased output in August by the most in eight months, helped by a robust month at auto plants. The gains are a hopeful sign that manufacturing could help boost economic growth in the second half of the year.

Manufacturing production rose 0.7 percent last month from July, the Federal Reserve said Monday. That's the biggest increase since December. It followed a 0.4 percent decline in July.

Automakers increased production 5.2 percent, after a 4.5 percent decline in July. And factories stepped up production of other goods, including computers and electronics, furniture and business equipment.