prosper tx is what county
Prosper, Texas. Homefacts City Report. Prosper is located in Collin County, TX. The population is 9,960, making Prosper the 6th largest city in Collin County. There are 8 public schools in Prosper with an average Homefacts rating of A+. The total crime rate for Prosper is very low, and there are 4 registered sex offenders residing in the city.