U.S. manufacturing growth powered to a 20-year high for a third straight month in January, but factories remained cautious about hiring, according to a report released on Monday.

The Institute for Supply Management said its manufacturing index rose to 63.6 in January from a revised reading of 63.4 the prior month. It was the first time since 1983 that the index had stood above 60 for three straight months.

But the reading was shy of economists’ expectations for a rise to 64.0. Any reading above 50 indicates expansion.

The index’s components slipped but showed the fast-paced growth is unlikely to slow much in coming months, as factories are still scrambling to keep up with demand for goods.

The new orders index fell to 71.1 from 73.1 the prior month but remains at some of the highest levels since the early 1970s. With orders still streaming in, the production index rose to 71.1 in January from 69.2.

But the robust activity has yet to spur more jobs, with the employment index slipping to 52.9 from 53.5 in December. With the employment index above the 50 level for a third month, some economists said U.S. manufacturing payrolls may rise in the Labor Department’s January employment report on Friday.

The ISM manufacturing report is based on monthly responses by purchasing executives at more than 400 industrial companies, from textiles and chemicals to paper and computers.