"Rapid growth occurred in the number of SEPs in the United States in the 1990s and early 2000s, followed by more incremental growth through 2008. The 123 SEPs participating in the 2008 survey reported operating in 98 cities† in 29 states and in DC."

Source

"Syringe Exchange Programs — United States, 2008," Morbidity and Mortality Weekly Report (Atlanta, GA: Centers for Disease Control, November 19, 2010) Vol. 59, No. 45, p. 1488.
http://www.cdc.gov/mmwr/pdf/w…