Of the five counties that have added the most people since 2010, only Ottawa County in western Michigan backed Republican Bill Schuette in last November’s governor race. The others, Oakland, Kent, Macomb and Washtenaw counties, supported the winner, Democrat Gretchen Whitmer.

In November, Michigan voters approved Proposal 2 to create a bipartisan citizens commission to draw the next political maps, taking that task away from legislators. When it convenes following the 2020 Census, the panel’s 13 members will be be tasked with drawing congressional and state Senate and House districts of roughly the same size.

And though the likely loss of a congressional seat will force a substantial redrawing of the state’s 14 districts into 13, the commission will also have to rearrange the 38 Senate and 110 House seats.

That’s when the musical chairs begin.

For instance, a Bridge analysis of U.S. Census population estimates shows the 110th House seat in the western counties of the Upper Peninsula has lost roughly 3,400 people since 2010, putting it below the number it would need in 2020 to balance the districts.

That means the 110th would have to add parts of neighboring 109th and 108th districts, which have lost a combined 5,000 themselves.

That sets off a cascading effect in which mapmakers would have to balance districts by drawing lines farther and farther south until they hit the state’s growing areas, often in areas where Democrats are predominant.

That means there likely would be fewer districts north of Bay City, where Democrats have struggled to win House seats for decades.

“(Democrats are) going to have a better chance,’’ said Kurt Metzger, a retired demographer who has long studied population trends in Michigan. “They have to be pleased insofar as they will get a better cut at this (because) it won’t be so obviously gerrymandered.”

The population changes continue a long-standing trend that would have benefited Democrats after redistricting in 2001 and 2011. Both years, though, the GOP controlled the governor’s office and Legislature, allowing them to draw legislative districts that now are considered among the most unfair in the country.

Republicans crafted districts that not only avoided electoral damage but made their position stronger: a Bridge analysis of the districts showed Republicans had an advantage in 67 seats going into the 2012 elections despite winning 63 seats in 2010.

“But for the actions of the Republicans gerrymandering this (population) shift would have been much more noticeable,” Lupher said. “They were able to mitigate it through gerrymandering.”

No more – unless they can persuade the Democrats and independents on the commission that gerrymandering in favor of the Republicans is a good thing, which is unlikely.

By a 61 percent majority, Michigan voters overwhelmingly approved Proposal 2 in November, which takes the power away from legislators and creates a bipartisan citizens’ committee to draw the maps in 2021.

The commission will be comprised of four Republicans, four Democrats and five independents. For a map to be approved, it must have at least two votes from each group.

If Democrats or Republicans controlled the 2021 redraw, they could easily turn it to their advantage, said Justin Levitt, a professor at Loyola Law School in Los Angeles who tracks redistricting.

Mapmakers create “districts to capture population you want to capture and you avoid those areas that makes your partisan team worse off,” Levitt said.

“That’s part of why Michiganders can feel really good about Prop 2,” he said. Those who have most to gain “don’t hold the pen.”

For instance, growing Democratic areas have been “packed” into already-Democratic leaning districts, minimizing their impact on neighboring districts.

A non-partisan commission, Levitt said, can draw boundaries that “are responsive to the communities but not engineered for partisan gain.”

“Where Job 1 is not looking out for the incumbent. And that’s not what’s happened in Michigan in the past,” he said.

Take Saline and Saline Township in southern Washtenaw County.

From 2000 to 2010, both were in the 17th state Senate district. That made sense – they adjoin one another and both are within the Saline Area School district.

But with Washtenaw County growing faster than nearby counties, the boundaries for a number of districts in the area needed to change.

So when Republicans drew the districts in 2011, Saline Township ended up in the 22nd Senate District and Saline city ended up in the 18th (the boundaries of the 17th moved east and south).

Here’s the political impact: Saline city, strongly Democratic, was put in the 18th District with Ann Arbor, which was already heavily Democratic; Democrat Jeff Irwin won in November with 77 percent of the vote.

And Saline Township? It leans Republican and ended up in the 22nd District, which Republican Lana Theis won with 56 percent of the vote. Republicans found a way to split the two communities in the most partisan way.

Demography will have less of an impact on perhaps the most important map, in terms of political power nationally – the congressional delegation.

Michigan lost a seat following the 2000 and 2010 Census counts and is expected to lose another after 2020.

In 2001 and in 2011, Republicans made sure the lost district was held by a Democrat and altered the boundaries so that they had a 9-5 advantage (which wasn’t erased until the so-called “blue wave” in November by Democrats evened the delegation to 7-7).

Southeast Michigan is home to seven districts and likely will lose one seat after 2020, Metzger predicted.

Since the two minority-majority districts, the 13th and 14th, are protected by the Voting Rights Act which prohibits the rewriting of boundaries that dilute the votes of racial groups, that puts the focus on the other five, four of which are represented by Democrats.