Found this in today's USA TODAY:
http://www.usatoday.com/news/nation/2010-11-22-bridges22_ST_N.htm
Do other states do this? Who owns the bridge, the state or the adopter?
The adopter usually ends up owning the bridge - some states require that it be transported to private property at that time. Michigan has a Historic Bridge Park (http://www.alpsroads.net/roads/mi/bridge).