Walt Whitman has been claimed as America's first "poet of democracy", a title meant to reflect his ability to write in a singularly American character. A British friend of Walt Whitman, Mary Smith Whitall Costelloe, wrote: "You cannot really understand America without Walt Whitman, without Leaves of Grass... He has expressed that civilization, 'up to date,' as he would say, and no student of the philosophy of history can do without him." Modernist poet Ezra Pound called Whitman "America's poet... He is America." Andrew Carnegie called him "the great poet of America so far". Whitman considered himself a messiah-like figure in poetry. Others agreed: one of his admirers, William Sloane Kennedy, speculated that "people will be celebrating the birth of Walt Whitman as they are now the birth of Christ".
The literary critic, Harold Bloom wrote, as the introduction for the 150th anniversary of Leaves of Grass:
If you are American, then Walt Whitman is your imaginative father and mother, even if, like myself, you have never composed a line of verse. You can nominate a fair number of literary works as candidates for the secular Scripture of the United States. They might include Melville's Moby-Dick, Twain's Adventures of Huckleberry Finn, and Emerson's two series of Essays and The Conduct of Life. None of those, not even Emerson's, are as central as the first edition of Leaves of Grass.
Whitman's vagabond lifestyle was adopted by the Beat movement and its leaders such as Allen Ginsberg and Jack Kerouac in the 1950s and 1960s as well as anti-war poets like Adrienne Rich and Gary Snyder. Lawrence Ferlinghetti numbered himself among Whitman's "wild children", and the title of his 1961 collection Starting from San Francisco is a deliberate reference to Whitman's Starting from Paumanok. Whitman also influenced Bram Stoker, author of Dracula, and was the model for the character of Dracula. Stoker said in his notes that Dracula represented the quintessential male which, to Stoker, was Whitman, with whom he corresponded until Whitman's death. Other admirers included the Eagle Street College, an informal group established in 1885 at the home of James William Wallace in Eagle Street, Bolton, to read and discuss the poetry of Whitman. The group subsequently became known as the Bolton Whitman Fellowship or Whitmanites. Its members held an annual 'Whitman Day' celebration around the poet's birthday.
Whitman's poetry has been set to music by a large number of composers; indeed it has been suggested his poetry has been set to music more than any other American poet except for Emily Dickinson and Henry Wadsworth Longfellow. Those who have set his poems to music have included John Adams, Leonard Bernstein, Benjamin Britten, Rhoda Coghill, Ronald Corp, George Crumb, Frederick Delius, Karl Amadeus Hartmann, Hans Werner Henze, Paul Hindemith, Ned Rorem, Ralph Vaughan Williams, Kurt Weill, and Roger Sessions. "Crossing," an opera composed by Matthew Aucoin and inspired by Whitman's Civil War diaries, premiered in 2015.
On May 16, 1957, the Walt Whitman Bridge, which crosses the Delaware River near his home in Camden, was opened.
In 1997, the Walt Whitman Community School opened, becoming the first private high school catering to LGBT youth.
In 2009, Whitman was inductucted into the New Jersey Hall of Fame.
In 2013, Whitman was inducted into the Legacy Walk, an outdoor public display that celebrates LGBT history and people.