If you have a planing
boat with a 400-500mile range (on plane), it's doable but will be pricey on fuel. It would likely be quicker if going
Alabama to Chicago.
If you have a sailboat or
displacement trawler, at best it's impractical and by most standards not possible (theoretically, you could make a herculean effort, slogging along a 1-2mph over ground hugging the shore to stay out of the worst of the current,
anchor, dingy to shore with 5 gal jugs multiple times but it's not going to be easy).
Barges have fuel range in the 1000's of miles and they have
commercial fueling options pleasure boats don't have. Plus due to their length, they have higher displacement speeds compared to most pleasure craft.
St. Louis to Kentucky lake is the critical section. North and south of there, locks control the currents (tenn-to to the south not on the Miss) to a degree and
marinas with fuel are plentiful. On this middle section, there is almost nothing for pleasure boats.
- It's about 200 miles down the Mississippi with currents ranging from 3-7 mph.
- Up the Ohio for around 50 miles fighting a 1-3 mph current.
- Up the Tennessee for about 20 miles fighting a 1-3 mph current.
Currents vary greatly depending on flood level and river geometry but as you can see almost 75% of the trip has you on the Mississippi with it's much higher down-bound current. If you
head south, it gives you a nice boost that more than makes up for the Ohio/Tenn but in the other direction, it means a lot of time fighting the heavier current.
Someone mentioned going up the
Hudson as a problem but you have to remember the Hudson is a tidal river. For around 120miles upriver, you can play the tide to actually get a boost going up river...plus there are plenty of docks/fuel stations, so even if slow, it's not a problem. The end of the tidal section is at a lock which limits the current upstream and you
wind up turning off onto the Erie shortly after.