A History of American Literature

This is a massive book, over 800 pages of text. I bought it because although I have read a fair amount of American literature there are a lot of gaps in my knowledge. In particular I had an interest in twentieth century poetry and also I was curious to know what a fresh look at literature could tell me about the development of the USA as a country over the last two hundred years.
I am not an academic and have not studied literature in an academic setting since I left school. Gray it seems to me adopts a narrative approach. His reading is immense and when he approaches an author his primary objective seems to be, what did they have to say.
One or two themes: literature in the nineteenth century often seems to be about the wilderness, the embrace of the wilderness, exploring it.
In the twentieth century there's a certain loss of meaning, an experience of alienation. The taming of the wilderness, the arise of the cities and railroads leaves Americans searching their souls for meaning. Especially the poets of the early century like Eliot, William Carlos Williams, Wallace Stevens etc.
I'm sure some readers will feel aggrieved that some authors have been skimped, but really I can't think of anyone he's left out.
A major achievement. Very unstuffy, and more than readable.