This poem deals with that big noble question of “How to make a difference in the world?” On first reading, it tells us that the choice one makes really does matter, ending: “I took the one less traveled by, / And that has made all the difference.”
A closer reading reveals that the lonely choice that was made earlier by our traveling narrator maybe wasn’t all that significant since both roads were pretty much the same anyway (“Had warn them really about the same”) and it is only in the remembering and retelling that it made a difference. We are left to ponder if the narrator had instead traveled down “The Road Not Taken” might it have also made a difference as well. In a sense, “The Road Not Taken” tears apart the traditional view of individualism, which hinges on the importance of choice, as in the case of democracy in general (choosing a candidate), as well as various constitutional freedoms: choice of religion, choice of words (freedom of speech), choice of group (freedom of assembly), and choice of source of information (freedom of press). For example, we might imagine a young man choosing between being a carpenter or a banker later seeing great significance in his choice to be a banker, but in fact there was not much in his original decision at all other than a passing fancy. In this, we see the universality of human beings: the roads leading to carpenter and banker being basically the same and the carpenter and bankers at the end of them—seeming like individuals who made significant choices—really being just part of the collective of the human race.
Then is this poem not about the question “How to make a difference in the world?” after all? No. It is still about this question. The ending is the most clear and striking part. If nothing else, readers are left with the impression that our narrator, who commands beautiful verse, profound imagery, and time itself (“ages and ages hence”) puts value on striving to make a difference. The striving is reconstituted and complicated here in reflection, but our hero wants to make a difference and so should we. That is why this is a great poem, from a basic or close reading perspective.