Economic activity in the non- manufacturing sector gained momentum in March, as the adverse impacts of the chilly weather began to wane, an industry survey showed on Thursday. The Non-Manufacturing Index (NMI), which measures activity in the U.S. service sector, registered 53.1 percent in March, 1.5 percentage points higher than February's reading, according to the Institute for Supply Management. The NMI survey covers all sectors outside of manufacturing. A reading above 50 percent indicates expansion of the service sector. The component for business activity index decreased to 53.4 percent, which is 1.2 percentage points lower than February's reading. The New Order Index, a signal of future business, edged up by 2.1 percentage points to 53.4 percent. The Employment Index increased 6.1 percentage points to 53.6 percent. Thirteen non-manufacturing industries reported growth, while five industries reported contraction. Despite the affects of weather on many of the respective businesses, the majority of respondents indicate that business conditions are improving. The respondents also project better business activity and economic conditions as weather conditions continue to improve. The NMI index is closely watched because the service sector provides about 90 percent of the U.S. workforce, and is a key indicator for the overall health of the economic recovery. Economic activity in the manufacturing sector also gained steam in March, as ISM reported on Tuesday that the purchasing managers index (PMI) increased to 53.7 percent.