Using United States public library statistics
This is neat! I wonder if we'd see significant change in the map if you were to look at attendance per child capita instead of per capita? Did you try it both ways?
Not yet. There might indeed be a difference, but I'm not sure how easy it is to find "children's population served" data for each library. Not in the PLS data certainly.
No info for Alaska and Hawaii?
Use the zoom out tool in the upper right corner.