Another universal concern developed in Twain's The Adventures of Huckleberry Finn is freedom.
Huck seeks freedom from a society that would attempt to control him. He wants freedom so badly that he rejects polite society to live with his Pap, even though his Pap is abusive. Huck only leaves the woods when his father tries to kill him and he has no choice. Huck says he will continue his running for freedom even when this story is over, rather than go back to society and try again. Huck runs away from the society that would control him, rather than toward something. Such is his need for freedom.
Of course, the need for freedom is inherent in Jim's situation. That hardly needs to be explained. Once again, however, it is polite society that would take his freedom.