Huck and Jim knew that they passed Cairo due to the number of towns that they passed. They also figured they passed it due to the fog.
Jim and Huck were trying to reach Cairo, Illinois so that Jim could attempt to escape to the free states and gain his freedom.
Huck and Jim go to Cairo in hopes of reaching a free state where Jim can gain his freedom. Cairo is near the northern border of a free state, making it a crucial waypoint in their journey to escape the bonds of slavery.
Jim is a runaway slave. If they were to get caught, Jim would be returned to Miss Watson in slavery and Huck would be scorned by the townspeople.
They know that they passed Cairo because they reach muddy waters of Ohio.
Huck was looking for the town of Cairo to help free Jim
They plan to drift down to Cairo.
Huck and Jim argue about English and French. Huck wants to learn French to look educated, while Jim argues that English is more important due to its widespread use in America.
Huck doesn't turn Jim in because Jim in Huck's first TRUE friend. Jim is also the only "family" Huck has ever had that cares so much about him and will protect him.
In the dense fog on the river, Huck and Jim miss their exit and end up floating past it, losing their way in the river's intricate twists and turns. They become disoriented and can't find their way back. Jim and Huck were trying to reach the city of Cairo in Illinois so Jim could get to the free states and be a free man.
There is never a reference to how he actually died in the novel. Jim and Huck just find a body in the house on the river. (Important to note that Jim turns Huck away from the body, as a way to protect him!)
He told Huck that Jim had been sold as a runaway slave!!!
Jim is initially startled when he sees Huck on the island, as he believes that he has seen a ghost. However, he quickly realizes that Huck is alive and is relieved to be reunited with him. Jim is happy to see Huck safe and well.