What is the overall mentality and "national character" of poetry in modern American literature?

I always hesitate to generalize art. Most movements are categorized more by time period than style, since even within close literary movements there are massive differences. Please be mindful that generalizations are dangerous and often inaccurate. That said, academics sometimes use generalizations to talk about periods of literature in broad strokes. Another thing to keep in mind is that the word "modern" means something different in literature than in daily life. It does not mean...

I always hesitate to generalize art. Most movements are categorized more by time period than style, since even within close literary movements there are massive differences. Please be mindful that generalizations are dangerous and often inaccurate. That said, academics sometimes use generalizations to talk about periods of literature in broad strokes. Another thing to keep in mind is that the word "modern" means something different in literature than in daily life. It does not mean current. It refers to a very specific period of the 20th Century. Today we are no longer in the Modern Period.

Modernism was characterized as a loss of the values represented in the prewar period. Contrary to the previous answer, I would actually say it was a rejection of early poets such as Whitman, who wrote about unity and American Exceptionalism. Modernism borrowed from thinkers such a Freud and Darwin to paint a word devoid of objective reality. The most important poet of this period would probably be T.S. Elliot. He  alluded to the great Western traditional while also abandoning the starry-eyed romanticism of the time before.

The Modern Period of American poetry was deeply intellectual, subjective, allusive, and difficult. Poets like Gertrude Stein abandoned earlier use of language as patriarchal. Poets like Pound turned to the past, and even looked to extremist politics as a solution to a world they say as crumbling. Despite large differences, most of the major writers seemed to question the very notion of American culture after the First World War. Artists rejected the early ways of seeing things, and painted a cynical America, where there was no clear difference between right and wrong. Many of these writers even left the country to work abroad. Once again, broad strokes are dangerous and inaccurate. Pound and Stein are in many ways as different as two writer can be. These are the sorts of traits that scholars typically use to discuss the time, however.