I agree with Joe about the escape route taken by Huck and Jim.

I also recall that another reason for going to Cairo is that Jim would stand
a better
chance of escape in a city large enough to have a chapter of an abolitonist
society or a
branch of the underground railroad.  Joel Chandler Harris writes of
"Patty-Rollers"
(Patrollers) in Georgia, which I'm sure existed in Missouri and Illinois as
well, who
patrolled, especially the border, looking for runaway slaves, seeking the
bounty as Joe
said or re-sale.  Jim could not know what type of people he might encounter
or whom he
could trust simply crossing and walking through unknown countryside without
knowing a
direction to take or a place to go; he might add to his chances of being
caught.
Aggitation that would result in the Fugitive Slave Act, intended to increase
or legalize
pressure on non-slave states to return runaways, is also already in the air.

Of course, Jim misses Cairo (Kay-row) and, as though it were Cairo (Ky-row),
finds
himself in danger of "being sold into Egypt" when they journey into the Deep
South
("sold down the river" is the phrase that often appears).

John Davis