Industrial production "edged down," the Fed said, dropping 0.1 percent.
Output in manufacturing, one of three industrial divisions, shrank 0.4 percent following an increase in April.
Production at mines rose 0.9 percent in May and output at utilities was up 0.8 percent.
Industrial production was 4.7 percent higher than in May 2011.
Capacity utilization -- measuring production as a percentage of manufacturing, mining and utilities operating at full steam -- fell to 79 percent, a 0.2 percent decline from its 1972-2011 average.
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