Adults in the US who use the text-messaging feature on their cell phone are 49% more likely than the average American to be between age 18-24, 14% more likely to be Hispanic and 24% more likely to be African American, according to (pdf) a survey from Scarborough Research.
The study also found that El Paso, Texas is the top US city for text messaging, with 57% of all adult cell-phone subscribers (age 18+) there reporting they use the text-messaging feature on their cell phone, compared with 48% of adult subscribers nationally.

Other leading markets for text messaging include Salt Lake City, Dallas and Memphis, Tenn., where 55% percent of cell subscribers use text-messaging.
Fort Myers, Fla., Charleston, W.Va., and Grand Rapids, Mich. are the local markets least likely to text message. Only 36% percent of Fort Meyers and Charleston cellular subscribers text, as do 35% of those in Grand Rapids, Mich.