There's plenty of material in the rest of the article that is even less convincing. Consider this:
"...the American Midwest is an agricultural breadbasket, not a large swamp, because railroads provided the link between that farming region and the demand of the East Coast..."
Does the author actually think the midwest was "a large swamp" prior to the arrival of settlers and the conversion to agriculture? Because it most certainly was not, unless the author thinks grasslands, savannas, and deciduous forests are the same thing as "a large swamp".
TFA was filled with sweeping generalizations like this, and mostly failed to substantiate any of them with references or other evidence. I imagine that this "large swamp" example wasn't the only case of pure BS.