HANNIBAL, Mo. - The Mississippi River, which flows from north to south in the United States, became an important commercial artery in the 19th century, with many steamboats sailing on it. Many small towns were built at ports along the river.
Hannibal, Missouri, in the Midwestern United States, is one such town.
Samuel Clemens, who would later become a famous American novelist under the pen name of Mark Twain, moved here with his family when he was 4. They lived in a two-story house about a five-minute walk from the river.
With no TV in those days, children played outdoors in nature. One favourite play spot was a cave at the edge of the town.
The cave, which stretches in many directions and has a total length of about five kilometers, is still there. In summer, 600 to 700 fans of the writer visit the cave from all over the world every day.
Inside the cave, graffiti done by children over the years remains. The scenes are very similar to those described in the climax of Twain's novel, "The Adventures of Tom Sawyer," published in 1876.
"Mark Twain played here as a child and that's where he got a lot of ideas for his stories," Sam Lucas, a 24-year-old guide in the town, said proudly.
Local people say Twain watched steamboats arrive at the riverside. Watching people and goods coming and going, a young Twain must have felt an increasing desire to find out about the outside world.
At age 17, Twain left the town and gained experience working at many jobs, including as a printer, newspaper reporter and a pilot for steamships, moving around the United States.
In the 1860s, Twain began traveling to Europe and the Middle East and also began writing novels and travel articles.
During Twain's childhood days, Hannibal was a typical rural town where there was still slavery.
Black slaves working at his home and in his relatives' houses were servants but also playmates of Twain. However, Twain learned during his wanderings in later years that there was a part of the world without slaves.
Henry Sweets, 65, the executive director of the Mark Twain Boyhood Home & Museum, explained that exposure to new cultures changed Twain's views about slaves that were accepted as a matter of course.
Another of Twain's major books, "Adventures of Huckleberry Finn," was published in 1885, nine years after "The Adventures of Tom Sawyer."
It is an adventure in which the title character tries to help Jim, a black slave who is gentle and honest, escape from his owner.
The text includes bad language used by children in those days, as well as terms of racial disparagement.
Twain did not refrain from using the discriminatory terms so that images of black people forced to live by obeying white people and other social realities of those years could be reproduced without understatement.
Because of this, "Adventures of Huckleberry Finn" has repeatedly stirred up controversy, though it is an excellent book for young people. In many parts of the United States, libraries have banned visitors from accessing copies of the book.
What did Twain want to convey through the story? Faye Dant, 65, who runs a museum of African-American history in Hannibal, said that even if the terms are regarded as discriminatory by today's standards, using them was necessary to convey the realities of those days.
Dant also said that Twain squarely faced the system of slavery and was one of the first white writers who gave personalities to black characters in novels.
Deep-rooted even now
A large-scale riot occurred last year in Ferguson, another Missouri city about 130 kilometers from Hannibal. It was triggered by an incident in which a white police officer shot to death a young black man.
The fact that Twain's novels are still being read even after their publication 130 years ago reflects how deeply rooted racial problems are in US society.
Mizuno is a correspondent in New York.
Twain's real name was Samuel Clemens. He was born in Florida, a city in Missouri. He lived in Hannibal in the same state, on the Mississippi River, from the ages of 4 to 17. After working as an apprentice at a newspaper, a steamboat crewman and at other jobs, Twain became a popular writer of travel articles. While working as a writer, he delivered lectures and speeches across the globe and is known for having left a large number of words of wisdom.