Throughout 1868, Twain and Olivia L

Throughout 1868, Twain and Olivia Langdon corresponded. Though she rejected his first marriage proposal, two months later, they were engaged. In February 1870, Twain and Langdon were married in Elmira, New York,[28] where he courted her and managed to overcome her father's initial reluctance.[30] She came from a "wealthy but liberal family", and through her, he met abolitionists, "socialists, principled atheists and activists for women's rights and social equality", including Harriet Beecher Stowe (his next-door neighbor in Hartford, Connecticut), Frederick Douglass, and the writer and utopian socialist William Dean Howells,[31] who became a long-time friend. The couple lived in Buffalo, New York, from 1869 to 1871. Twain owned a stake in the Buffalo Express newspaper and worked as an editor and writer. While they were living in Buffalo, their son Langdon died of diphtheria at age 19 months. They had three daughters: Susy (1872–1896), Clara (1874–1962)[32] and Jean (1880–1909). The couple's marriage lasted 34 years, until Olivia's death in 1904. All of the Clemens family are buried in Elmira's Woodlawn Cemetery.

Twain moved his family to Hartford, Connecticut, where starting in 1873 he arranged the building of a home. In the 1870s and 1880s, Twain and his family summered at Quarry Farm, the home of Olivia's sister, Susan Crane.[33][34] In 1874,[33] Susan had a study built apart from the main house so that her brother-in-law would have a quiet place in which to write. Also, Twain smoked pipes constantly, and Susan Crane did not wish him to do so in her house. During his seventeen years in Hartford (1874–1891) and over twenty summers at Quarry Farm, Twain wrote many of his classic novels, among them The Adventures of Tom Sawyer (1876), The Prince and the Pauper (1881), Life on the Mississippi (1883), Adventures of Huckleberry Finn (1885) and A Connecticut Yankee in King Arthur's Court (1889).

Twain made a second tour of Europe, described in the 1880 book A Tramp Abroad. His tour included a stay in Heidelberg from May 6 until July 23, 1878, and a visit to London.