The U.S. economy remained mired in recession in March, according to the national activity index published monthly by the Federal Reserve Bank of Chicago, MarketWatch reported.

The three-month average for the index improved marginally to negative 3.27 from negative 3.57 in February and negative 3.69 in January, which was the lowest since 1975.

Any reading under zero indicates below-average growth. Readings below negative 0.70 usually mark a recession. The index is designed to measure current economic activity and shows “little inflation pressure from economic activity over the coming year,” the Chicago Fed said.

The monthly index, which is volatile and subject to revisions, fell to negative 2.96 in March from negative 2.82 in February. It was negative 4.03 in January. All four major categories of the economy declined in March, led by employment.

The index is constructed from 85 economic indicators measuring employment, production and income, consumption and housing, and sales and inventories. Of the 85 indicators, 13 made positive contributions in March.

The Conference Board reported today that its index of economic indicators declined 0.3 percent in March, following a 0.2 percent decrease in February and a 0.2 percent decline in January.

“The recession may continue through the summer, but the intensity will ease. There have been some intermittent signs of improvement in the economy in April, but the leading economic index and most of its components are still pointing down,” Ken Goldstein, a Conference Board economist, said in a news release.