The U.S. manufacturing sector maintained its robust growth in May, according to the latest monthly survey of supply executives.

The Institute for Supply Management's poll registered a Purchasing Managers' Index of 54.9 percent, which was slightly above April's level and, at more than 50 percent for the ninth consecutive month, indicated continued growth in the manufacturing economy.

The PMI also translated to eight consecutive years of growth in the overall economy.

The May survey showed a new orders index of 59.5 percent — a 2 percentage point increase compared to April — and a production index of 57.1 percent, which was down compared to the previously month. Both orders and production increased for the ninth consecutive month.

Employment, meanwhile, climbed for the eighth consecutive month as the index increased 1.5 percentage points to 53.5 percent.

Raw materials inventories continued to grow last month, but customer inventories remained too low for the eighth month in a row — although the latter index edged toward the 50 percent threshold.

Supplier deliveries also slowed for the 13th consecutive month, which analysts said showed that supply chains are adjusting to higher levels of demand.

The prices index slid by eight percentage points but remained high at 60.5 percent in May. ISM Manufacturing Business Survey Committee Chairman Timothy Fiore said that the higher prices seen in 2016 are showing signs of moderation.

"The slowing of pricing pressure, especially in basic commodities, should have a positive impact on margins and buying policies as this moderation moves up the value chain," Fiore said.