[JohnnyZ]

Philip K. Dick, the greatest American writer of the 20th century. Most important too.

Drawing a blank on other good 20th Century American authors.

Guess that says something right there.

Willa Cather? Pearl S. Buck? Steinbeck.... T.S. Eliot, if he counts as ours. Hemingway, Faulkner, Richard Wright, Flannery O'Connor .... hmm. Yikes.

Graham Greene and Tolkien blow that crowd out of the water from across the pond, that's for sure.

[Oberon]

Drawing a blank on other good 20th Century American authors.

Ray Bradbury. Yes, he's an LA liberal, but boy can he write a story. He also appropriated from Shakespeare what is perhaps the coolest title for a novel ever: Something Wicked This Way Comes.

[Ueriah]

I like PKD quite a bit.

Check out Harlan Ellison for another good 20th Century author.

[Sam Cree]

Mark Helprin qualifies, IMO, as a great American writer of the 20th century.