Jonesboro is a city in Grant County, Indiana, United States, located along the Mississinewa River opposite Gas City. The population was 1,756 at the 2010 census. According to the 2010 census, Jonesboro had the third smallest population of a city in Indiana.

Grant County is a county in central Indiana in the United States Midwest. At the time of the 2020 census, the population was 66,674. The county seat is Marion. Important paleontological discoveries, dating from the Pliocene epoch, have been made at the Pipe Creek Sinkhole in Grant County.