http://ngrams.googlelabs.com/

and type in “United States are, United States is”)

And on exactly that subject, here’s Ben Zimmer taking on Shelby Foote:

http://www.visualthesaurus.com/cm/wordroutes/1907/

When I was directing for WFMY-TV in Greensboro, we did an interview program called “Newsmaker” and in early 1973 we interviewed North Carolina’s then newly elected Senator Jesse Helms. Jesse related the following story. Upon his arrival in Washington, he was greeted by a veteran Senator from “out West.” ( Helms didn’t give a name). “Welcome to Washington, Senator Helms. We haven’t seen many Republican Senators from North Carolina,” the veteran said. “Have you lived in North Carolina all your life?” “Nope, not yet,” replied Jesse. The Senator from out west continued, “Well, I’ll bet you guys grow a lot of grits down there in North Carolina. Are those grits hard to grow?” Helms replied,, “they’re not hard to grow, but they’re hell to shell.”

The other grits story also comes from my days at WFMY. A couple of years after Jesse’s visit, I was directing the late news one Friday night. When we got off duty about midnight, several of us decided to go out to this all-night diner and get breakfast. When we arrived, one of my crew members checked out the menu and didn’t see grits listed. He then asked the waitress, “do you guys serve grits?” The waitress replied, “Honey, we’ll serve anybody.”