The formative period 1910s-1920s
The first flowering of modern poetry 1930s-1940s
The modernist movement and surrealism 1950s-1960s
Underground poetry, nativism, and women's voices 1970s-1980s
The anti-sublime and multiculturalism 1980s-1990s
New lyricism and postmodernist experiments, The new millenium.