 The only major change to occur in the district boundaries prior to the 1990s occurred in 1866, when a trapezoidal section of Union District in Mason County, including the village of Rockcastle and the headwaters of Thirteenmile Creek, was transferred to Jackson County, and attached to Ripley District.Otherwise, the names and boundaries of the historic districts remained largely unchanged for over a hundred and twenty years.In the 1990s, Jackson County was redistricted in order to equalize the area and population of its magisterial districts as nearly as possible.