Hi Allison
Straight from the book!
"You can use your badge when travelling in the European Union but concessions do vary. .... There are no current arrangements for you to use the badge outside the European Union, in countries such as the USA, Canada, Australia or New Zealand, although they may be prepared to recognise the Blue Badge."
Have a look at
this it might be of some help! Also
this page for California.
Hope you get some luck with it
Lyn x