In 1907, Dodge became engaged and married to (Ethel) Geraldine Rockefeller of 689 Fifth Avenue. She was a child of William and Almira Geraldine Goodsell Rockefeller, and was estimated to have her own fortune of more than 100 million dollars. They were said to be the wealthiest newlyweds in the country when they married. Initially, when they resided in New Jersey, they lived together at "Hartley Farms", a country estate in New Vernon purchased by Marcellus and his aunt, Helen Hartley Jenkins, in 1904.