What is the significance of the setting of The Road Not Taken?
The poem is about a guy in the woods, and he comes across a fork in the road.
Two roads diverged in a yellow wood...
One of the roads is more well traveled than the other, and the narrator decides to take the road that is less well traveled. If you have ever been on a hike through some forested area, I'm sure that you have seen many trails that are exactly like what the narrator describes. Both trails have their pros and cons. You have to pick one, and you know that you are not likely to get to come back and choose the other trail. It's a common occurrence.
The location doesn't take on any kind of special significance until you "English teacher it." The fork in the road is a metaphor for any "crossroads of life" that a person has. At some point in a person's life there is going to be a decision (or many decisions) to be made between two equally appealing choices. One has to be chosen knowing that the other choice will cease to be an option after the decision is made.
The poem says that choosing the less traveled road has made all of the difference. That's an important detail to notice. Actually, it's the lack of detail that is important to notice. The narrator doesn't say whether or not the choice made a good or bad difference. It's the same thing with life decisions. Sometimes a single decision will have far reaching and vast repercussions (good and bad). Well, of course that choice has made all of the difference then.