How about doing a large center block of the US and coloring in all the states she went through. You could easily print a page, enlarge it to size, and color it in. I would think she could go back and color in more states in the future as long as she remembered to heat set them.
http://www.apples4theteacher.com/col...ional/usa.html
You could then do some border blocks representing things she saw along the way.