My first thought was, "Um, duh?"
My second thought was a little heavier. I remembered doing research a year earlier for a college paper about the Washington Redskins and the sports mascot debate. For many people, the portrayals of American Indians in movies, television, halftime shows, books and cartoons may be the only "contact" they ever have with the American Indian culture. The context of the stories told about American Indians is almost always in the past tense, in a past time, contributing to a subconscious thought that American Indians no longer exist and/or are part of fairy tales.
That's why the exhibit at the museum felt compelled to explain to its visitors that American Indians exist today--you just might not recognize them because they're in hard hats and suits.