History of 19th-century congressional redistricting in Ohio
The redistricting of United States congressional districts is made by the legislatures of the states every 10 years, immediately following the official announcement of the federal census that serves as the basis of the apportionment. It was long the practice that the apportionment thus made stood until after the next decennial census.
Source: Wikipedia — History of 19th-century congressional redistricting in Ohio (CC BY-SA 4.0)