The increasing cost of prom has put celebrating the big night prohibitively expensive for many girls. Local programs like The Princess Project in the Bay area have sprung up to address this need and collect proms, purses, and accessories to give out to those in need.
There are many other local programs, including:
Georgia, Atlanta: The Enchanted Closet
Multiple Locations:: The Glass Slipper Project
Multiple Locations: Donate My Dress
Are none of these near you? Donation Town might be able to help you find a spot for your dress.