Cities and counties in at least 13 states report successful results after enacting a breed-specific ordinance.

These states include: Arkansas, California, Colorado, Iowa, Kansas, Maryland, Michigan, Missouri, Nebraska, Pennsylvania, Rhode Island, Washington and Wisconsin.

View an extensive list of cities that have successfully enacted BSL:

http://blog.dogsbite.org/2010/06/cities-with-successful-pit-bull-laws.html

Also see Where are pit bulls banned