The Ceridian-UCLA Pulse of Commerce Index gained 3.1 percent in May, the largest monthly boost in over 10 years.
From last year, the PCI was up 9 percent, the sixth straight year-over-year gain for the index.

The PCI represents real-time diesel fuel consumption data from over-the-road trucking tracked by Ceridian, a provider of electronic and stored value card payment services and human resources solutions.

Following a slight decrease in April, the index grew from 108.1 in April to 111.4 in May.

"Absent good news from the usual recovery indicators - consumer optimism expressed by buying homes and cars, and business optimism expressed by hiring - the spike in the PCI is indeed very welcome news for the economy," said Ed Leamer, the PCI's chief economist. "One month does not make a trend, but at least we are back in a recovery groove."

Ceridian says the PCI closely tracks the Federal Reserve's monthly Industrial Production index. The most recent PCI predicts Industrial Production to grow by 0.85 percent in May. The Federal Reserve will release May figures on June 16.

All regions the index tracks also saw strong growth, with the exception of the Middle Atlantic region, which saw a 0.8 to 0.6 percent drop.

"The uptick in trucking activity during the month was apparent nationwide," said Craig Manson, senior vice president and index expert for Ceridian. "More importantly, even though we're still well below 2008 levels, the positive year-over-year growth trend in the index over the past six months is encouraging."

For more information about the index, visit www.ceridianindex.com.