How does Frost employ settings of rural life in "Birches"?

The way that this poem gets readers thinking about rural life is through its descriptions of how people interact with the birch trees themselves or do things that are stereotypically associated with simple, rural life. Line 3 is a good place to start looking for specific rural setting activities.

I like to think some boy's been swinging them.

The narrator is thinking about a boy swinging from the branches of birch trees. It's not like trees don't exist in urban settings. They do, and kids climb those trees as well; however, the notion of spending an afternoon climbing trees and swinging from branches should make most readers think of a rural setting or at the very least family camping trips. The country has more trees, so there is more opportunity for this kind of thing.
About midway through the poem, readers get another example of a boy in the country. Again the narrator comments about the boy bending tree branches, but this time the boy is doing it on his way to fetch the cows. Immediately after this line, Frost is fairly blunt about the boy's setting. He is too far from town to play baseball (presumably on some kind of team).

Some boy too far from town to learn baseball,
Whose only play was what he found himself,
Summer or winter, and could play alone.