A few simple observations: The United States is large. Americans buy things often. So, all kinds of goods get hauled over great distances all the time. And, once again, FRED has some relevant data.
The graph tracks various modes of transportation for freight. And even though these indicators have different units (tons, short tons, ton-miles, and barrels), FRED’s graphing flexibility lets us compare them in a logical way. Once we change the units to an index, setting all values at 100 starting in the year 2000, we can compare the evolution of these indicators over time. It looks like freight hauled by rail is slowly but surely losing its market share, while freight hauled by trucks has fared better. Freight on U.S. waterways has partially recovered from earlier losses, and pipeline transport has recently increased. Airborne freight is more difficult to judge: The jump in 2002 reflects a change in the indicator itself, when more carriers were included in the calculation; but it looks stable since then, except for the big dip during the recent recession.
How this graph was created: These series can be found in the U.S. transportation data release. Select the relevant series and click “Add to Graph.” Because so many different units are used for these series, unify them by scaling the units to 100 for the date 2000-01-01: Open the “Edit Graph” tab, look in the “Units” menu, and choose “Index (scale value to 100 for chosen date).”
Suggested by Christian Zimmermann.