As a leader in truck leasing and logistics, when Ryder System (NYSE:R) announced fourth-quarter earnings last week, it got me thinking about what the company's business says about the state of the economy. Logically, if manufacturing output is increasing, then truck leasing would be, too. Thus, so should Ryder's revenues.

Ryder's revenues rose by less than half a percent to $4.80 billion from $4.78 billion. By contrast, the U.S. Census Bureau's statistics on manufactured durable goods indicated that from Dec. 2002 through Dec. 2003, new orders increased 6.49% and shipments grew by 8.17%. That's a significant difference.

But it's just one company. Any number of reasons other than demand could have an impact on revenues, such as mergers and acquisitions, or entering and exiting markets. While that doesn't appear to be the case here, looking at a few more shipping-related companies provides a clearer picture.

The latest revenues on Dow Jones Transportation Average companies CSX (NYSE:CSX), J.B. Hunt Transport Services (NASDAQ:JBHT), Norfolk Southern (NYSE:NSC), United Parcel Services (NYSE:UPS), Yellow Roadway (NASDAQ:YELL), and Ryder, showed an average increase of 4.08%. That's closer, but still a far cry from the 8.17% increase in shipments the government reported.

So what gives? Part of the difference might be explained by manufacturers taking up slack shipping capacity internally, without turning to transport companies. Or perhaps the difference could be that U.S. manufacturers are increasingly producing and shipping goods overseas that never enter the U.S., and hence, do not translate into revenues for U.S. transportation companies. Or for that matter, jobs.

The results do seem to jive with the various reports showing continued weak employment in manufacturing, while output and productivity are on the rise.

Most importantly though, what it does show is that the economy probably isn't growing as robustly as the government's numbers are indicating, at least from the perspective of the average American. And that much of the economic growth we have seen thus far has been the result of international commerce and largely limited to U.S. multinational companies. The good news is that the weak dollar and corporate profits should begin to trickle down and translate into more jobs over the course of the year.

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Motley Fool contributor Mark Mahorney is an antagonist residing in Denver. He promises to respond cynically to all emails.