In 1856, Arthur courted Ellen Herndon, the daughter of William Lewis Herndon, a Virginia naval officer. The two were soon engaged to be married. Later that year, he started a new law partnership with a friend, Henry D. Gardiner, and traveled with him to Kansas to consider purchasing land and setting up a law practice there. At that time, the state was the scene of a brutal struggle between pro-slavery and anti-slavery forces, and Arthur lined up firmly with the latter. The rough frontier life did not agree with the genteel New Yorkers; after three or four months the two young lawyers returned to New York City, where Arthur comforted his fiancée after her father was lost at sea in the wreck of the SS Central America. In 1859, they were married at Calvary Episcopal Church in Manhattan. After his marriage, Arthur devoted his efforts to building his law practice, but also found time to engage in Republican party politics. He also indulged his military interest by becoming Judge-Advocate-General for the Second Brigade of the New York Militia.
The Arthurs had two sons, one of whom died young, and a daughter:
William Lewis Herndon Arthur (1860–1863)
Chester Alan Arthur II (1864–1937) - He graduated from Princeton University in 1885 and went on to Columbia Law School. He became a gentleman of leisure. President Arthur on his deathbed warned his son not to go into politics. Alan Arthur traveled extensively, maintained a fine stable of horses, and relied on polo for exercise. A celebrated playboy, at age 36 he married Myra Townsend Fithian, a California heiress. The couple separated after 16 years of marriage and divorced in 1927. Eventually he settled in Colorado Springs. In 1934 he married Rowena Graves, a real estate and insurance businesswoman.
Ellen Hansbrough Herndon Arthur (1871–1915) - Still a child while her father was president, she was shielded from the press. She married Charles Pinkerton and lived in New York City.