Assonance is the repetition of vowel sounds in words that are close to each other in a literary work, generally within the same poetic line or nearby lines. Sometimes words that show assonance rhyme or also exhibit alliteration (the repetition of initial sounds), and sometimes they don't. Let's look at some examples of assonance in Carl Sandburg's poem “The Harbor.”

In the first line, we have assonance between “huddled” and “ugly” on the u sound. This sound actually echoes throughout the poem in words like “hunger” and in repetitions of all three of these words. The sound appears again in “sudden,” “under,” and “sun.” This sound is almost a moan, so it is quite appropriate to the subject matter of the poem that describes the suffering of the city's poor.

Assonance also occurs in the words “doorways” and “haggard” in the poem's second line as well as “lake waves breaking.” The long a sound appears again in “spray” and “great gray.”

As the poem draws to a close, the poet continues to insert assonance as in “flying” and “white.” In the final line, he chooses the long e in “veering,” “wheeling,” and “free.”

All of the assonance adds to the poem's linguistic interest and contributes to its vividness. As we said above, it even reflects the content to a point. The e sound, for instance, is long and flying, and this mimics the flight of the gulls.