Most Important American Plays

A few months ago, my playwright friend Elaine Romero told me about a friend of hers, John Moore, who was doing a survey among theatre people to see what they thought the most important American plays were, for The Denver Post. The plays had to be ranked, 1 through 10. I passed this onto some other theatre friends, as I'm sure many of the respondents did.
This was a really difficult exercise. Because it wasn't what plays you like most, or are the most emotionally affected by, but which you think are "most important," starting in 1776 to the present day. Is Fashion by Anna Mowatt important because it's the first play by an American woman? Is Here We Are by Dorothy Parker important just because I think it's nearly flawless, though it's adapted from a short story and it's only one-act? Is "Death of a Salesman" important because it's thought to be Miller's iconic play, even though I've never been that wild about it? I also wonder if some of it has to do with age; not so much old vs. young, but when I was in college the young-ish playwrights writing in English who we really looked up to were Sam Shepherd and John Guare, and to a lesser extent Jean-Claude van Itallie. Albee was different- there was no question that he was already in the canon.
The link to the survey is above. I can tell you that the top ten most important plays on that list that were not on mine (I can't find mine at the moment) were Death of a Salesman, A Raisin in the Sun and The Crucible. The plays I remember really wrestling with myself about including were The Curse of the Starving Class, The Little Foxes, and You Can't Take It With You (there are no comedies on the top ten list).