American author Walt Whitman was best known for writing in which genre?

Walt Whitman is America’s world poet—a latter-day successor to Homer, Virgil, Dante, and Shakespeare. In Leaves of Grass, he celebrated democracy, nature, love, and friendship. Along with Emily Dickinson, Whitman is regarded as one of America’s most significant 19th-century poets and would influence later many poets. While his poetry failed to garner popular attention from his American readership during his lifetime, over 1,000 people came to view his funeral. And as the first writer of truly American poetry, Whitman’s legacy endures.

Source: Poetry Foundation