Mark Twain had four children with Olivia Langdon Clemens: Langdon, Susy, Clara, and Jean.
The family’s only son, Langdon Clemens, was born in 1870 and died of diphtheria in 1872 at about 19 months old. Their three daughters were Olivia Susan “Susy” Clemens, born in 1872; Clara Langdon Clemens, born in 1874; and Jane Lampton “Jean” Clemens, born in 1880.
Because Langdon died so young, some brief biographies mention only Twain’s three surviving daughters. That can create confusion, but the standard count includes all four children born to Twain and Olivia. Twain’s family life was marked by repeated loss: Susy died in 1896 at age 24, and Jean died in 1909 at age 29. Clara was the only child to outlive her father.
Twain married Olivia in Elmira, New York, in 1870. Their children were born during periods when the family lived in Buffalo, Hartford, and elsewhere, and the family maintained a particularly strong connection to Elmira, where several members are buried.