Louisa Cornelia (Seward) Canfield was born in 1805 in Florida, New York, daughter of Samuel Swazy and Mary (Jennings) Seward and younger sister of William H. Seward. She attended Emma Willard's Troy Female Seminary in Troy, New York, where Frances Miller was her classmate. The two women became friends and Frances met her future husband, William H. Seward, during a visit to her home in Florida. On April 18, 1827, Louisa married her father's student and an aspiring doctor, Mahlon Dickerson Canfield. The marriage seems to have been clouded by the unhappiness of Louisa's father over the arrangement. The couple moved to Bargaintown, New Jersey. Louisa and Mahlon had five children. Frances Seward recounts in a letter written to her sister Lazette Worden, dated January 12, 1839, that Louisa died of Quinsy, a peritonsillar abscess. Louisa died on January 4, 1839.