Yes, they did have a crime family in cowboy country. The Dallas crime family was formed in 1921. They were a small group with 25-30 made members. Their major rackets were drugs, prostitution and gambling.

The first boss was Carlo Piranio, a Sicilian mafioso who moved to Dallas in 1920. Carlo died of natural causes in 1930. His younger brother Joseph succeeded him as boss. Joseph Piranio ruled the small family for many years. He was a well connected strip club and bar owner. Joseph shot himself in the head with a handgun October 27, 1956. Joseph Civello took over the family after his death. He was a very close friend of New Orleans family boss Carlos Marcello. Civello was one of many mob leaders busted at the famous Apalachin mob meeting in 1957. He ruled over Dallas until he died of cancer January 17, 1970. Joseph Campisi succeeded him as boss. Him and his brother Sam were the owners of the Egyptian Lounge. It was the first Italian restaurant to open up in Dallas in 1949. Campisi was also a friend of mob associate Jack Ruby. They say Ruby ate at the restaurant the night before the Kennedy assassination. Campisi was arrested once for murder in 1944, but the charges were later dropped. He was connected to Trafficante family bosses Santo Trafficante Jr. and Joseph Loscalzo. In 1989, Campisi was awarded a certificate from the city of Dallas for his outstanding community service. He past away in 1990 from a heart attack after chasing a bus boy out of his restaurant accused of stealing money.

I got all my information from various mafia articles and books, but if you're looking for a source similar to this check out dieland mob at http://members.fortunecity.com/sosdie/mob/family/dallas/dallas.htm