The first edition of Robert Frost’s third collection of poems, Mountain Interval, was published in 1916 by Henry Holt and Company and was dedicated “To you who least need reminding that before this interval of the South Branch under black mountains, there was another interval, the Upper at Plymouth, where we walked in spring beyond the covered bridge; but that the first interval of all was the old farm, our brook interval, so called by the man we had it from in sale.” The “you” Frost refers to is his wife, Elinore, to whom he dedicated most of his books. The “South Branch” is the Frosts’ farm in Franconia, New Hampshire. The “Upper at Plymouth” is a reference to their time spent together in Plymouth, New Hampshire. “The first interval” is another reference to time spent together, this time in Derry, New Hampshire. And the brook is Hyla Brook, by Frost’s farm in Derry, which provided the title of one of the poems in this volume. According to Jay Parini in his biography of Robert Frost, Robert Frost: A Life (1999), an interval is a “New England dialect term for land in a valley.” Therefore “mountain interval” provides a double meaning, suggesting a “pause in a journey as well as a dip in the landscape” (278). “The Road Not Taken” opens the volume and perhaps makes reference to this “mountain interval.”

Initially the collection did not sell as many copies as Frost’s previous collection, North of Boston, probably because his publisher rushed the book into print. Nevertheless, it contains some of Frost’s best-known and most celebrated poems, such as “The Road Not Taken,” “Birches,” and “Out, Out—.” Frost wrote the majority of the poems during his stay in England; whereas he wrote a few before leaving for Europe and reworked them for book publication, such as “Birches” and “Putting in the Seed.”

Naturally, Frost was disappointed by the book’s lack of sales, but it was to be expected of a third volume following so quickly on the heels of two previous collections, A Boy’s Will and North of Boston. Despite the book’s abysmal sales figures, most scholars agree that it was a seminal book in the history of modern poetry, virtually on the basis of “The Road Not Taken” and “Birches.”