Schertz is a city in Guadalupe, Bexar, and Comal counties in the U.S. state of Texas. It has a population of about 41.000 and a median income of about $59.000. It’s the third largest city of a metropolitan area surrounding a local Air Force base. It was established in 1843. The city has an annual jazz festival, and an annual fundraiser event in March benefiting the University of Texas Health Science Center at San Antonio's Cancer Therapy and Research Center. This is a 5K walk and fun run. Steve Earle - alternative country rocker, grew up in Schertz.