Whitney's was the best. I do not understand why they do not make it clear to the artist who is given the honor of singing at the time of their selection what is expected is a straight rendition with no ad-libs or histrionics. In the sound check if the artist goes off plan chuck them and have the Whitney record or some military band play over the sound system.

Actually, the artist is required to submit a recording of the intended rendition to the NFL in the week before the game, for the league's approval.

Furthermore, the Star Spangled Banner is a horrible melody (as BB Jake noted, it's an old English drinking song originally titled "To Anachrion in Heaven"), with an insane octave and a fifth range, which is challenging even for a trained vocalist. It really hasn't been the official National Anthem all that long--only since the 1930s. Many people favor replacing it with America the Beautiful. Myself included.

On top of all that, Fort McHenry aside, the Brits basically kicked our asses during the War of 1812. They captured Washington, DC, and burned the White House. The greatest American victory, the Battle of New Orleans, came after the war was officially over.

It was sort of, "unfunny". Sitting there, waiting for her to screw the lyrics up. Then I said, nah, she's way too good for that.
Not.
She had her haters before. A few more now. A bad day at the office for her camp.

I'd have to add the Dixie Chicks to the top rungs of the "best rendition of". Very nice harmony on one tough to sing song.

YouTube - Dixie Chicks National Anthem

At the other end of the spectrum and for some additional cringe worthy singing, don't forget Carl Lewis. "Uh-oh..."

YouTube - Carl Lewis National Anthem

two of the talented ladies in this video are 6 years old, another one is 7, the oldest is 9...

they sing much much better than C.A....

AND..they know the words...

the NFL should pay these young ladies whatever it was the gave C.A.

to sing it next year..

YouTube - The Cactus Cuties sing The National Anthem Original Video

here here
good show

I agree we should expect better from a pro but I am willing to leave some room for "I was nervous and lost my place" , or " I was thinkin about the improvisations I was adding and forgot where I was in the song". etc. Making mistakes is human. I even made a mistake once when I thought I had made an error but really hadn't. :) Everyone makes Mistakes , it doesn't make them unAmerican. Let he who is without sin cast the first stone.

I also agree that it is an extremely difficult song to sing. Not the words but the tune is rediculous for most peoples vocal range. "America the Beautiful" is a great song and i think that except for the tradition that supports "The Star Spangled Banner" , we would have changed to "America the Beautiful" or "God Bless America" (civil liberties group would challenge that) a long time ago.