Growth has been choppy since the U.S. economy pulled out of recession two years ago, alternating between lukewarm and anemic expansion.
Most economists have minimized the likelihood that the U.S. or global economies will fall into decline again, but economic data and shipment volumes at freight carriers in recent weeks have raised worries the economy is stalling.
Some of the initial warning signs are coming from a slow-down in business at companies that transport goods. Trucking and other transport modes are leading indicators of economic activity, usually showing upturns or downturns several months ahead of the broader economy.
Some experts suggest weak growth is normal and that the economy and shipments will rebound in the second half of the year. But for the first time since the 2008 financial crisis, the dreaded term "double dip" is being whispered - and it doesn't refer to the number of scoops at the local ice cream parlor.
