I had assumed that in the hash creation, that the constants would be interpolated into their text values.

The tokens WISCONSON and ILLINOIS are being treated as "barewords", thanks to '=>'. To force them to be interpeted, you can do something like

  my %capitol_map = (
      (WISCONSON) => "Madison",
      ...
[download]

or risk a bit of duplication and write

  my %capitol_map = (
      WI => "Madison",
      ...
[download]