Jasper County is a county located in the US state of Iowa. As of the 2010 census, the population was 36,842. The county seat is Newton. The county was organized in 1846 and is named after Sergeant William Jasper, a Revolutionary War hero.Jasper County comprises the Newton, IA Micropolitan Statistical Area, which is part of the Des Moines-Ames-West Des Moines, IA Combined Statistical Area.