Although most people alive today think of the United States as a major world power, historically, both the United States and Canada were colonized by Europeans. Thus, when we think of contemporary literatures in England and the United States, we are considering cultures that were shaped by different experiences, despite their sharing a common language.
English literature is essentially colonial and European, reflecting a long continuous history as an imperial power. England, however, is no longer the great imperial power it was in the nineteenth century and much English literary reflection is devoted to the question of whether England should in response to this emphasize her own Englishness, retreating from internationalism, as advocated by Philip Larkin, or whether it should it embrace international postmodernism, either of a European or American flavor.
The literature of the United States, on the other hand, reflects a postcolonial experience. First, it attempted to imitate the European models to avoid being considered a provincial backwater, but slowly began to assert cultural as well as political independence by either embracing regionalism (as is the case with Southern Gothic, prairie, and other regional movements) or arguing for new cultural forms to suit a new continent, as one can see in traditions stemming from Whitman and progressing through the Beats to many forms of contemporary writing. Also, American contemporary literature has begun to embrace cultural diversity, honoring the unique contributions of Native Americans, African Americans, Latino/Latina writers, and Asian Americans.