We Americans have yet to really learn our own antecedents, and sort them, to unify them. They will be found ampler than has been supposed, and in widely different sources. Thus far, impress'd by New England writers and schoolmasters, we tacitly abandon ourselves to the notion that our United States has been fashion'd from the British Islands only, and essentially form a second England only — which is a very great mistake.

"The Spanish Element in Our Nationality," letter to the Philadelphia Press (20 July 1883), later published in The Complete Prose Works of Walt Whitman (1892), part V: November Boughs

4. The Spanish Element in Our Nationality. November Boughs. Whitman, Walt. 1892. Prose Works[bartleby.com]