Nathan Davis Stanwood was born on October 18, 1817, in Ipswich, Massachusetts, the son of Jacob Stanwood (1785-1845) and his second wife, Sally Caldwell. In 1820, the family moved to Augusta, Maine, where Nathan's father worked as a wool merchant. On January 1, 1844, Nathan married Martha Jane Delano, daughter of Lemuel Delano and Nancy Eastman of Strong, Maine. Martha died just three years after the marriage, on October 15, 1847.
Stanwood held several occupations in the 1840s, including shopkeeper, itinerant daguerreotypist, and beginning in 1849, gold miner. He left New England for California in November 1849, and mined in Calaveras until 1852, when he abandoned mining for a series of ventures including a salmon fishing business and a meat retail venture called the "Boston Market." On January 1, 1857, he married Maine-native Emily S. Barrell, who sailed to California to marry him. They had two children: Elijah (b. ca. 1860) and Edith (b. ca. 1864). By 1864, Stanwood lived in San Francisco and worked as a secretary for the post office. He later served as a delegate in the 1867 Alabama Constitutional Convention and as a member of the Alabama House of Representatives. He died March 27, 1879.