Year-over-year growth approached 10%, the level Leamer says is necessary to support enough economic growth to decrease unemployment.

FORBES: Truckers Say Market's Wrong, Economy Grows

Meanwhile, the rising truck traffic indicates GDP growth of 3% to 5% in the second quarter, Leamer says, not enough to make a big dent in unemployment but enough to return the U.S. economy to its long-term trend of 3% growth by 2013.

FORBES: Truckers Say Market's Wrong, Economy Grows