And too, these rivers explain why the US was so slow to build railroads and roads. It’s hard to compete with river transport.

There’s a difference between transportation types. Cargo traffic requires only maximal throughput at minimal cost. Passenger traffic requires speed.
Mark Twain in his Mississippi book had some notes on the dynamics of river/rail transport development. Once both were developed enough, the river had lots of cargo barges, but only marginal passenger traffic compared to what it used to be. Trains took all the passengers.

It’s even more obvious with air transport. While it remained too expensive for most cargo that could be moved in any other way (up to and including dog sleds), the spread of passenger planes took a lot passenger traffic from rail.

Anyway, water transport reach is among the conditions in which the railroad network develops. Even when navigable rivers are numerous, they don’t go everywhere. But since the steamer/barge backbone had much greater capability, the role of railroads was to connect ports of different navigable rivers and reach from them into all the places barges could not go.

Later and on another continent…

Stalin had some remarkable masters of logistics placed where they could do much (read Grigorenko on Apanasenko — he does not get attention, but he was the man behind both all those Far East divisions appearing right in time and Japanese reluctance to open second front).
He wanted to develop rail as best as possible, find the best men for this. And eventually had rail logistics organized and refined as much as possible at this time. But he also demanded canals, to use the rivers more.

In the conditions when railroad was all-important either way, barges still mattered on strategic level, so much that even expensive ways to make river transport more useful became high-priority projects.

And too, these rivers explain why the US was so slow to build railroads and roads. It’s hard to compete with river transport.

We must be careful when we explain history to ourselves.

On this subject, didn’t the Chinese build a significant canal that’s been in operation for some time now? Is that their trick for making so many people?

And, on this subject, how did the south-Asian Indians manage to create so many people, given their land?

Fun things to think about.

The wealth of internal distribution options the United States enjoys means that for the bulk of its history American dependence upon the international trade system has been less than 15 percent of GDP.

“GDP” is laughable bullshit. The author is not a stable genius. Other than this, well, duh. It’s almost an entire continent.