The monthly index known as the Chicago Fed National Activity Index rose from minus 0.29 in May to minus 0.13 in June. The three-month rolling average for the index -- less volatile than the month-to-month reading -- also rose, climbing from minus 0.37 in May to minus 0.26 in June.
The index is a broad measurement of U.S. business activity, using a weighted average of 85 indicators based in four main categories: Production and income; employment, unemployment and hours; personal consumption and housing; and sales orders and inventories.
The index uses zero to represent average growth. As such, June's index shows growth slightly below the historic trend.
The Chicago Fed said 41 of 85 indicators made positive contributions in June, while 44 made negative contributions.
Notable deaths of 2014 [PHOTOS]