Ohio voters approved a redistricting reform ballot measure Tuesday that will change how congressional districts are drawn, a move advocates say would curb excessive partisan gerrymandering.

The details: The new process, which had overwhelming bipartisan support, will go into effect in 2021 when the next round of redistricting takes place. While it still puts redistricting in the hands of lawmakers, the measure would prevent one party from having overwhelming power over the redrawing and approval of electoral lines. Ohio is said to be one of the most pro-Republican-gerrymandered states in the country.

How it works: When the legislature draws new maps to align with 2020 U.S. Census figures, it will now need three-fifths support from each chamber and at least one-third from the minority party.

If lawmakers fail to approve a plan, the bipartisan Ohio Redistricting Commission would take over the process and create either a 10-year map with minority consent or a four-year map without.

The backdrop: This comes as some states are locked in major redistricting battles over extreme partisan gerrymandered maps, and grassroots campaigns in others to limit political redistricting. The U.S. Supreme Court is expected to decide two cases by June that could, for the first time, impose constitutional limits on gerrymandering.