James Moseley Crosby, son of Moreau Stephen Crosby (1839-1893) and Mary Elizabeth Moseley (1844-1939), was born in Grand Rapids, Michigan July 6, 1867 in the family home at 212 Fountain Street. He graduated from Central High School and received an engineering degree from the University of Michigan in 1891. James returned to Grand Rapids and began working for the Valley City Milling Company until the death of his father in 1893. At that time he took over J.S. Crosby&Co., the insurance company his father and grandfather, James Sears Crosby (1813-1875), began in 1858. By 1910 James M. had moved J.S. Crosby&Co. to the Barnhart Building at Louis and Ionia.

James married Louise Vickery Barnhart (1874-1959) in 1900 and together they had six children. His son, James M. Crosby, Jr. (1901-1973), joined him in his insurance business and eventually became the President of the Michigan Association of Insurance Agents. Moreau S. Crosby (1902-1977) became a local insurance agent for Provident Mutual Life Insurance Company. Willard Barnhart Crosby (1904-1957) went into the publishing business in New York City. Elizabeth Crosby (1903-1998) attended Vassar College, married Richard Bachmann and moved to Detroit. James and Louise's youngest child, Mary Louise Crosby (1915-2006), also went to Vassar College and then married Campbell H. Steketee in 1937. John Raymond Crosby was born to James and Louise in 1908 and died in 1910 before three years of age.

James M. Crosby was a member of St. Mark's Church and served on the Board of Education in Grand Rapids. He was also a founding member of the Kent County Chapter of the Sons of the American Revolution. He died March 9, 1952 and is buried at Oakhill Cemetery.

James M. Crosby, Jr. married Anna H. Lyon in 1926 and continued his career at J.S. Crosby&Co. After serving in the US Air Force and receiving an accounting degree at Syracuse University their son, James M. Crosby III, began his public accounting career in Detroit and later returned to Grand Rapids to join the family business. Jim married Elizabeth Joan Muir in 1959. He and Betty Jo had three sons together, James, William and John. In 1970 the Crosby agency merged with TenBroek-Henry, a local insurance agency founded in 1868. At the time of his death in 1992, James Crosby III was president of Crosby&Henry..