I can't think of much of this movie, except that the president of the USA's wife, was injured after some kind of disaster, and a woman driving something like a tractor like Cal trans workers would use, or maybe it was a huge dump truck located this woman and saved her. Though I believe at the end of the movie, the 1rst lady died.
Any clues? Thanks.

Sounds like Independence Day (1996) (http://www.youtube.com/watch?v=EeT6QgmxEjs)

Must be Independence Day

Thank you. I rented it today to be sure, and it was Independence day. :)