"The cards would be mandatory for all "federal purposes," which include boarding an airplane or walking into a federal building, nuclear facility or national park, Homeland Security Secretary Michael Chertoff told the National Conference of State Legislatures last week.
Citizens in states that don't comply with the new rules will have to use passports for federal purposes." http://www.crooksandliars.com/2007/08/16/open-thread-no-national-parks-without-a-passport-bud/
