Born in New York City to Irish immigrant parents, John Daniel Crimmins attended the College of St. Francis Xavier (now Xavier High School). After graduating he took a job at his father’s contracting firm, eventually taking over the business. His firm employed some 12,000 workers. It built more than 400 buildings in New York City and most of the elevated railways. He was also involved in local politics, serving as New York City Parks Commissioner. Crimmins was one of the few Catholic millionaires of his time and he was an active benefactor of the Archdiocese of New York. Among the building projects he aided was that of St. Joseph’s Seminary, Yonkers. Crimmins was named a Knight Commander of the Order of St. Gregory the Great and a Papal Count. He was active in Irish-American organizations, particularly the American-Irish Historical Society. He wrote two books on Irish-American history.