I don't really know how to answer this question, simply because the concepts "American" and "poetry" are confusing to me. What I find interesting, though, is that such a question is being asked at this historical moment. It is usually in moments of historical crisis that people start wondering about the Americanness of America, and that poets start investigating the Americanness of what they do. The runup to the Civil War produced Whitman, and the sixties were defined by an enormous number of poems that addressed America and Americannness. Since we're living through what is essentially a reprise of the Gilded Age, I wonder what the crisis in American identity is which is prompting questions like the one being asked. Maybe the worst crisis is having no crisis at all.