This map shows the flow of all domestic freight between states in 2015 using data from the Freight Analysis Framework, which is a comprehensive accounting of all commercial freight movement between states by all modes of transportation. This includes freight moved by trucks, trains, planes and pipelines, but excludes foreign imports and exports and freights transported within a state.

How to read it: The arrows represent the origin and destination of goods shipped between states. Thicker and darker arrows indicate higher volume (each commodity is scaled relative to the highest volume between any two states, so arrow size isn't comparable across commodities).

Expand chart Note: The Standard Classification descriptions can be deceptively narrow but often cover large groups of goods. Complete documentation is available here; Data: Center for Transportation Analysis; Graphic: Chris Canipe / Axios

Some relationships are head-scratchers at first glance. For instance, the Alcoholic beverages category shows an outsize role for Iowa, which is not necessarily known for its beer and wine industry. But the full category description covers "denatured" alcohol, which includes corn-based ethanol.

Some anomalies may be explained by steps within a supply chain. A manufacturer in California may ship to a wholesaler in Missouri, who then ships to a retailer in Texas. Some raw materials go through a distillery or rendering process before shipping elsewhere for sale or consumption. But then why is so much building stone shipped from Texas to Alabama?

Do you have an explanation for other state-to-state routes that look out of place? Send me an email at canipe@axios.com. I'd love to hear from you.

What else we saw: