WASHINGTON (AP) — U.S. service companies grew in January at the slowest pace in six months, amid concern over the impact of the partial government shutdown on the economy.

The Institute for Supply Management, an association of purchasing managers, reports that its service index fell to 56.7 percent last month, down from 58 percent in December. The January reading was the lowest since July 2018.

Any reading above 50 signals growth. So even with the January decline, the index shows that service industries, where most Americans work, has been expanding for 108 consecutive months. The ISM notes that executives of service companies remain optimistic about overall business conditions.