I also have ancestors listed in "central institute." After looking at various web sites and maps of Elmore County, I believe that central institute is merely a postal district named after an historic school called the "Central Institute." From its map coordinates find that "Central Institute" would have been 6 miles from the center of Eclectic. So the designation must have just been a convent way to map out a district for the census takers, with an enumeration district that merely followed the postal sorting routes. Bill McCain