How does the setting of the book The Adventures of Tom Sawyer impact the characters and/or the story ?

Twain's setting on the Mississippi River is essential in
formulating the tone of the novel. Set in the 1840s, the fictional town of St. Petersburg,
Missouri is still on the western fringes of America. The people are unsophisticated and far from
the large cities found farther east; however, they are a close-knit society, where everyone knows
one another and they come to each other's assistance when needed. The river setting is important
for the pirate theme, and the ease with which the boys can escape from their little town into the
relative wilds adds to their exploits and adventures.