Massachusetts

Massachusetts is the commonwealth that Fallout 4 is set in. Despite confusion, Massachusetts is shown in Fallout 4 as being a commonwealth, as shown on loading screen menus

Known locations
The Commonwealth
 * Glowing Sea (Fallout 4)
 * Boston (Fallout 4)
 * Bunker Hill (Fallout 4)
 * Concord (Fallout 4)
 * Museum of Freedom (Fallout 4)
 * Sanctuary Hills (Fallout 4)
 * Vault 111 (Fallout 4)
 * Diamond City (Fallout 4)
 * The Institute (Appears in Fallout 4, mentioned in Fallout 3 and ''Fallout: New Vegas)
 * Lexington (Fallout 4)
 * Paul Revere Monument (Fallout 4)
 * Quincy (Fallout 4)
 * Salem (Appears in Fallout 4, Mentioned in Mothership Zeta)
 * Scollay Square (Fallout 4)

Appearances
Massachusetts is only in Fallout 4, and mentioned in Fallout 3 as well as it's add ons.