The main theme of Langston Hughes’s poem “Harlem” is that forcing another person to delay the achievement of their dreams, or being forced to delay one’s dreams, can have devastating and wide-reaching effects.
The speaker asks a number of questions in response to the initial one: “What happens to a dream deferred?” (line 1). First, he asks if it simply dries up, like a raisin left out in the sun? This would make the raisin fairly unpalatable. Next, he asks if the deferred dream will “fester like a sore” that oozes pus or blood—a pretty uncomfortable and gross idea. Third, he asks if the delayed dream will begin to “stink like rotten meat,” or, fourth, if it will “crust and sugar over” like some too-sweet dessert left to sit out and get old. Neither would be edible or enjoyable. Next, the speaker suggests that the dream will begin to wear on a person, to become a burden “like a heavy load” would. Each of these five comparisons uses a simile to compare the deferred dream to something else, something unpleasant.
Finally, the speaker asks, “Or does it explode?” This line is set apart, on its own, as well as italicized (which provides emphasis), and it is also the only metaphor in the poem, comparing the deferred dream to something that would explode, like a bomb. For these reasons, we might surmise that this is the real answer, the truest answer to the first question. The speaker’s other suggestions as to what happens to a deferred dream are much smaller, affecting only one person or place, but a bomb affects many people and can be terribly destructive to a large area. This leads us to the poem’s main idea: that a deferred dream doesn’t simply die or wither away; it builds in pressure until there is a figurative explosion, perhaps of anger or resentment.
That the poem is called “Harlem” leads to the related idea that the dream of racial equality for Black Americans cannot be deferred without causing destruction and harm. Harlem is a predominantly Black borough of New York City. One could read the poem as a warning that, if Black Americans’ dream of equity and fairness is deferred by white society, the effects will be devastating for all.