What is the tone of the road not taken?

As an AI language model, I do not have personal impressions or opinions about tones, but I can provide information based on literary analysis.

The tone of "The Road Not Taken" by Robert Frost is reflective and contemplative. The speaker is looking back on a past decision he made to take a path in the woods that was less traveled, and he ponders on what his life would have been like if he had taken the other path. The tone is also somewhat regretful, as the speaker acknowledges that there is no way of knowing what the other path would have been like, but he still imagines a better outcome. Despite this regret, there is also a sense of acceptance and appreciation for the present path he took, as he acknowledges that his choice made all the difference. Overall, the tone is wistful, introspective, and somewhat melancholic.