U.S. manufacturing activity grew at a faster pace in January due to an increase in new orders and more hiring at factories, a trade group said in its monthly report released Friday. The Institute for Supply Management (ISM) said its index of manufacturing activity jumped to 53.1 last month from 50.2 in December. It was the highest reading since April, when the index reached 54.1. Any reading above 50 indicates expansion, while a reading below 50 signifies contraction. The second consecutive monthly increase in the index showed manufacturing is beginning to expand again after struggling through most of 2012. Increased uncertainty about tax increases and government spending cuts led many companies to reduce orders for machinery and equipment, and a weaker global economy limited demand for U.S. exports. Manufacturers added 4,000 jobs in January, the fourth consecutive monthly increase. The survey's new-orders index returned to growth, rising to 53.3 from 49.7 in December. Companies also reported adding to their inventories in January following two months of declines, a sign that factories are preparing to increase production. The ISM report showed that 13 of the 18 industries surveyed grew last month, including manufacturers of plastics and rubber, textiles, furniture, printing, and clothing. Four industries reported contraction—minerals, computers and electronics, wood, and chemicals.