The vast $700-billion US trucking industry with its 3.4 million drivers that hauled 10 billion tons last year — 69% of the nation’s freight — is an early warning system for the overall economy. And it’s been making the wrong rumbling sounds.

Rates for intermodal containers by rail dropped on a year over year basis in January, February, and March, according to the Cass Intermodal Price Index by Cass Information Systems (CASS – Get Report). April hasn’t been released yet. Cass tried to explain the March decline this way: railroads were facing weaker demand and losing pricing power as shippers were shifting loads to trucks because diesel has gotten cheaper.

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