Uncle Sam I Am

Who is this Uncle Sam? And why ain't he around? I search from state to state, But he's nowhere to be found I've looked in every corner, Of the good ole USA. In Shreveport and Chicago, From New York to L.A. I've driven every highway, And all the roads between them. All the people on the streets, I ask them if they've seen him. This confusion hurts my head, I don't know what to do. Every sign that I've read, Says Uncle Sam Wants You!