The Adventures of Huckleberry Finn
by Mark Twain (1884)
Huck Finn, cruelly abused by his drunken father, joins up with Jim, a runaway slave, and heads down the Mississippi River on a raft. Along the way, they encounter a deadly feud, a pair of con artists, and other characters from the pre-Civil War South. All the while, Huck's conscience and basic decency wrestle with his society-bred ideas about race and slavery and right and wrong.
If you like this book, try:
The Adventures of Tom Sawyer by Mark Twain
Tuck Everlasting by Natalie Babbitt
To Kill a Mockingbird by Harper Lee