John had lofty political aspirations

Dickinson believed that she would make a wonderful wife and partner since she had inherited a substantial inheritance. On July 19, 1770, Dickinson wed Mary Norris, also known as Polly, a well-known and intelligent thirty-year-old Philadelphia woman with a sizable holding of real estate and personal property (including a 1,500-volume library, one of the largest in the colonies at the time), who had been managing her family's estate. She was the daughter of Isaac Norris, Speaker of the Pennsylvania General Assembly, and a rich Quaker from Philadelphia.

Additionally, she was related to the Quaker poet Hannah Griffitts. Dickinson stated that he believed in the "lawfulness of defensive war," which is why he never officially joined the Quaker Meeting. In a civil ceremony, he and Norris were wed. Only two of Dickinson and Norris' five children Sarah Norris "Sally" Dickinson and Maria Mary Dickinson lived to maturity. They resided in Fair Hill, a neighborhood close to Germantown in Philadelphia, which they renovated with their combined fortune. The Dickinsons were able to strengthen their social and political ties with this marriage, especially in their hometown of Philadelphia. Only two years later, his political career was picking up speed, and he was chosen to represent Philadelphia in the Pennsylvania Assembly.