Granger, Indiana. Homefacts City Report. Granger is located in St. Joseph County, IN. The population is 27,656, making Granger the 3rd largest city in St. Joseph County. There are 5 public schools in Granger with an average Homefacts rating of A+. The total crime rate for Granger is moderate, and there are 12 registered sex offenders residing in the city.