Fallout 4 “appears to be set in Boston”, according to casting documents obtained by Kotaku.
The documents are for a casting call for a project codenamed Institute. While they do not reference the Fallout series directly, several references to “setting and locations” from the franchise appear throughout it. Kotaku also reports that the casting director for Institute is linked to previous projects at Bethesda Game Studio.
In August 2012, an anonymous Reddit poster claimed Bethesda had been visiting Boston locations. In January, 2013 Fallout 3 voice actor Erik Dellums wrote on Twitter that there “may be more of the Dog coming”, referencing his character from the game, DJ Three Dog.