Michigan voters passed a constitutional amendment Tuesday designed to limit excessive partisan gerrymandering in the state, taking the power to draw state legislative and congressional lines away from lawmakers and giving it to an independent commission.

The win is significant because Michigan is currently considered one of the most gerrymandered states in the country. Republicans controlled the redistricting process in 2011 and ruthlessly gerrymandered districts to give the GOP an advantage for the next decade. They have consistently won nine of the states 14 congressional seats even though Barack Obama carried the state in 2012 and President Donald Trump barely won it in 2016 . An analysis by the Brennan Center for Justice estimates gerrymandering in Michigan is responsible for an additional two to three seats in Congress.

Giving an independent commission control over drawing state and congressional lines, advocates say, will ensure that no party can manipulate the redistricting process, done once every 10 years, to its severe advantage.

Anyone in Michigan can apply to serve on the panel, and the secretary of state will also send out 10,000 random mailers to people inviting them to apply. The panel will consist of four Democrats, four Republicans and five independents. There are restrictions intended to limit partisanship. No one who has served as a lobbyist, candidate or officeholder within six years can serve on the commission. Commissioners also cant be related to anyone who has served in any of those roles. Once selected, the commissioners are barred from holding elected office for five years after serving on the body.

The panel is required to hold at least 10 public hearings to solicit input on maps as they draw them. The amendment also outlines specific criteria for drawing electoral districts, including that they be compact and contiguous and dont disproportionately favor or hurt incumbents, candidates and political parties. Recently released emails from 2011 show Republicans discussing cramming Dem garbage into certain districts and officials discussing tweaking district lines to satisfy incumbents .

The success of the ballot measure comes after the U.S. Supreme Court passed on an opportunity in June to set limits on partisan gerrymandering. Ballot measures, like the one in Michigan, could offer a way forward for advocates to go around the federal courts and set limits on partisan gerrymandering.

The win is the culmination of a grassroots effort that started with a single Facebook post and grew to earn the backing of major voting rights groups. Republicans fought in court to keep the measure off the ballot. The main opposition to the measure came from a group funded almost entirely by the Freedom Fund , a group linked to the family of Education Secretary Betsy DeVos that pushed Michigan to adopt a right-to-work law. The group backing the amendment also received support from dark money groups .

The push for the amendment started with a Facebook post from Katie Fahey, a program coordinator at the Michigan Recycling Coalition, after the 2016 election. She heard back from more people than she thought and had more than 10,000 people gather signatures to get the measure on the ballot.

In an interview last year, Fahey said the measure was intended to protect both political parties.

If you just read our policy, it directly says one political party cannot take advantage of the other when drawing these maps. It has to actually be fair and representative of how the people of Michigan vote, she said.