Massachusetts

Massachusetts was a state of the United States of America. It was one of the thirteen British colonies prior to the American War of Independence. The First Doctor, Susan, Ian and Barbara visited Massachusetts in 1692. (PDA: The Witch Hunters) During the American Civil War, Claire Bartlett lived in Diensberg from which she sent several letters to her lover Will Johnson. Johnson hoped to settle in Diensberg with Bartlett after the war and to become the manager of that town's steelworks. (TN: Blood and Hope)

Janet Rae Tanner's parents Gerald and Elaine Tanner lived in Nantucket, Massachusetts in the late 20th and/or early 21st century.

Behind the scenes
MIT, mentioned in K9TV: The Custodians, probably refers to the in Cambridge, Mass. Also located in Cambridge is Harvard University.