In case of a super-volcano, what would America do

Theoretically speaking,
what if one day the super volcano in yellow stone park(?) erupted
and lava went all across the country.

How would officials react?
And what would us the people do?
Would we have to get on planes and fly to another country?

P.S Please do correct me of any mistakes.

Actually lava would not go across the country, lava would be fairly localized (by fairly I mean covering an area about three times the size of Yellowstone NP) however, the ash that would be produced would rise into the atmosphere and cause a nuclear winter like effect causing global temperatures to drop considerably (causing lots of problems with native species, game meat animals, crops, livestock, etc. Not to mention the blanket of ash that would cover parts of North America.

If you live within about 500 miles you should be concerned about lava flows, if you live within about 1500ish miles you should worry about ash fall, if you live on Earth you should be worried about ash induced nuclear winter.

I answered this recently.
http://answers.yahoo.com/question/index;…
What would happen if the supervolcano at yellowstone national park erupted?

Basically think of it as the end of life as we know it.