The only significant descriptions of Salem which Arthur Miller provides in The Crucible are found in the pages of narrative rather than in the play itself. Here Miller talks about the primary characters as well as the setting and thinking of the town, and he clearly depicts isolation in his description.
Miller describes Salem as "a few small-windowed, dark houses snuggling against the raw Massachusetts winter." This small town battles the elements alone at the edge of the ocean. Miller adds that "the edge of the wilderness was close by." Now we see that Salem is surrounded on one side by the ocean and on another by wilderness and forest, a place which suggests evil and danger as well as physical isolation.
Miller's description of the people adds to the sense of isolation he is creating. They do not celebrate holidays and gather mostly just for religious activities; they are jealous of each other and are even willing, as we soon discover, to make false accusations against their neighbors if they think they will benefit from doing so. This is a kind of social isolation which Miller claims is one of the precipitating factors in the witch trials.
Salem's physical location and social structure--as well as their chosen system of government and religious beliefs--all contribute to its isolation.