The U.S. manufacturing sector expanded at the slowest pace in over a year in September amid weaker auto sales and a slumping housing market.

The Institute for Supply Management said today its manufacturing index registered 52.9 in September, below August’s reading of 54.5 and the lowest reading since May 2005.

Analysts had been expecting a reading of 53.5.

A reading of 50 or more indicates expansion, while below 50 shows contraction, and September was the 40th straight month of growth.

In the ISM report, the purchasing managers’ cost index fell to 61.0 in September from 73.0 in the previous month as commodity prices took a tumble.

The ISM new-orders index was flat at 54.2 but the order-backlog index fell to 46.5 in September from 51.5 in August.

Also, the ISM employment index dropped to 49.4 in September from 54.0 in August.

In other U.S. economic data released today, spending on construction projects unexpectedly edged up 0.3% in August. The best gain in nonresidential activity in 11 months offset another big decline in home building.

The overall August increase followed a steep 1% decline in July and represented the best showing in five months.