For the mystics of that world, choosing Salem Town in Boston is because it is the sanctum of mystics.
This is the last place where "magic" and "gods" appeared, the final resting place of the Ancient Gods. Innumerable mystics have found information about super-ancient times here in Salem and deciphered brand new ceremonies, which have even become treasures of some schools of thought to this day.
In Boston, the relics of the Divine Era, whether it's the "Smoke Mirror" from North American mythology or the Sun God "Feathered Serpent God," are present. Many colonists preserved these relics of the Divine Era under the guise of "protection" in their museums, facilitating the study of mysticism.
