The speaker, presumably Robert Frost himself, is driving in a sleigh drawn by a single horse. It is snowing. He is struck by the beauty of a particular stand of trees and stops to look at them. He seems to be feeling a little guilty about doing this. He is afraid of being seen by the man who owns the trees. Many commentators have taken what one critic calls the "criminal patina" in the poem to indicate that the speaker is thinking of committing suicide by letting himself freeze to death in the snow. Jeffery Meyers, in his biography of Frost, writes:
The theme of “Stopping by Woods” despite Frost‟s disclaimer--is the temptation of death, even suicide, symbolized by the woods that are filling up with snow on the darkest evening of the year. The speaker...wants to lie down and let the snow cover and bury him.
Whose woods these are I think I know.
His house is in the village, though;
He will not see me stopping here
To watch his woods fill up with snow.
This alternative explanation suggests that these must be fir trees, and most likely either Balsam firs or Fraser firs. New Hampshire is famous for its spectacular fall foliage, but by the winter solstice its deciduous trees would be “bare ruined choirs where late the sweet birds sang.” Evergreens, however, look especially picturesque with their boughs bending under virgin snow. According to the New Hampshire Christmas Tree Promotion Board:
Christmas trees are grown all over New Hampshire, from the rugged Great North Woods above the White Mountains [where Frost lived for many years] to the scenic Lakes Region, in the pastoral Monadnock area and on to the farms of the Merrimack Valley and the Seacoast. Most of the farms are family owned and operated and range in size from less than an acre to 100 acres in size. The New Hampshire farms grow a number of different species of Christmas trees, although Balsam fir and Fraser fir are the most numerous.
So the speaker only wants to spend a few minutes looking at the beautiful trees as the green branches are covered by the white snow. Frost makes his poem dramatic by suggesting that there is something more sinister involved.
Everything written is as good as it is dramatic. It need not declare itself in form, but it is drama or nothing. -Robert Frost