WASHINGTON -- Manufacturing activity in the Chicago region in March retreated from high levels reached in February, according to media reports of the purchasing managers index for the Chicago region recently released. The Chicago purchasing managers index fell to 58.8% from 62.6% in February. Economists had been anticipating a retreat but this was a bigger decline than expected. Forecasters surveyed by MarketWatch had expected the index to fall to 59.9%. Still, the report signals solid growth. Readings over 50% indicate overall business expansion. The Chicago index had surged over the winter as the U.S. manufacturing rebound gathered strength. The Chicago PMI is also considered a leading indicator to the national Institute for Supply Management manufacturers' survey for March to be released. Economists expect the March ISM manufacturing composite to increase to 57.0 from a February reading of 56.5.