WASHINGTON (AP) — Wholesale companies added to their stockpiles for a 17th straight month in May but their sales declined for only the second time in the past 11 months, providing further evidence of the U.S. economy's slowdown in the spring.

The Commerce Department says wholesale inventories rose 1.8 percent in May, the biggest gain since October. Some of that increase reflected an unwanted buildup of goods because sales declined.

Sales at the wholesale level fell 0.2 percent. The sales drop was led by a big decline in auto sales and the inventory buildup also reflected a large rise in auto stockpiles.

The weakness in May sales was just the latest evidence that the economy slowed in the spring as consumers struggled with soaring gas prices and high unemployment.