Don't forget the Ohio, the Wabash, the Missouri, the Susquehanna, the Delaware, the Allegheny, the Illinois, and hundreds of other tributaries.
That about covers water, but what about 2200 miles of borders? And that only covers trade routes with the North. What about the 1000 mile border with the West? Piece of cake Non?
Toss in the Great Lakes, too, while you are at it because one thing that they have in common with the rivers you mentioned was that they lay entirely within the United States. You propose to smuggle the good to the US through the US? Neat trick.
That about covers water, but what about 2200 miles of borders?
Sure, what are you going to do? Hide them in a semi and take them down a back road? Come on, Pea! Goods in the volume we are talking about either moved by water or rail or they didn't move at all. Paved roads didn't exist outside of cities. So that means we are back to the Mississippi and the few rail lines that connected North with South. That is the only way that 99% of the imports could have moved. Watching them would have been a piece of cake.