Mark Twain was born Samuel Langhorne Clemens in tiny Florida, Missouri on November 30, 1835. He was the sixth child of John and Jane Clemens, one of five boys and two girls. By the time Mark Twain reached his third birthday, his sister, Margaret, had died; by Twain's ninth birthday, his brother Benjamin had also passed away. Twain's birth came at a time in America when river travel was just reaching the point of passenger transport and major commercial shipping by water. This new industry would greatly influence this soon-to-be author's life in many ways.

The Clemens family was never financially secure, so Mark Twain's birthdays were never celebratory events. At Delmonico's Steak House in New York City at his seventieth birthday party, Mark Twain described the date of his birth:

I have had a great many birthdays in my time. I remember the first one very well, and I always think of it with indignation; everything was so crude, unaesthetic, primeval. Nothing like this at all. No proper appreciative preparation made; nothing really ready. Now, for a person born with high and delicate instincts - why, even the cradle wasn't whitewashed - nothing ready at all. I hadn't any hair, I hadn't any teeth, I hadn't any clothes.

Florida, Missouri: Mark Twain's place of birth

When Mark Twain was born, Florida, Missouri was still a young, small town which had only been off the planning board for four years before his date of birth. Florida was founded by men who had an interest in developing a revenue and employment center; each of the founding fathers owned a business or provided a service, such as being a doctor. It was the developer's hope that Florida would become an important commercial shipping location given the town's prime location at the forks of the Salt River. John Clemens, Mark's father, invested in the Salt River Navigation Company with the hope that the small town would become a growth center for northeast Missouri. Due to irregular river levels on the Salt, however, the boom never reached Florida, and it remained the small town it was when Twain was born in 1835. Seeking a better life for his family, John Clemens moved his family to Hannibal, Missouri when Sam was four years old.

Even after the family had relocated to Hannibal, Mark Twain continued to visit his birthplace, staying at the farm of his uncle, John Quarles. These return visits to the place of his birth and the social life he enjoyed on and around the farm, particularly with the house servants, became the bases for many of the perspectives Twain wrote about in his novels. The farmhouse remains as a tribute to the author's place of birth.

Mark Twain once said of Florida, Missouri, which he always referred to as a "village" versus a town: "The village contained a hundred people and I increased the population by 1 per cent. It is more than many of the best men in history could have done for a town."