Most states treat redistricting like typical legislation, meaning the governor can sign or veto the legislature's maps; a veto will often lead to a court drawing new lines if no compromise can be reached. Some states have remedied this problem by creating independent redistricting commissions, but some farm the process out to boards filled with political appointees, and in many cases, the governor determines which party is in control. Others will see governors make appointments to the state’s highest court, which may be crucial for determining whether excessively partisan maps survive judicial review.

The states included above are those that meet these criteria:

Governor’s influence : A Democratic governor must be able to impact redistricting in one of three ways: The governor can veto an unacceptable map and plausibly expect to have that veto sustained by the legislature; The governor has the ability to influence a redistricting commission’s partisan lean; OR The governor will determine the ideological control of a state supreme court majority by the time of redistricting .

Competitiveness : If the decisive gubernatorial election is in 2018, Daily Kos Elections currently rates it as something other than “Safe” for one candidate

: If the Meaningful impact: The difference between a partisan gerrymander and fairer map could foreseeably swing one seat or more , either in Congress or in the state legislature, or both.

That yields a list of 25 states, 19 of which host elections in 2018. Of these, Arizona, Florida, Georgia, Illinois, Michigan, Ohio, Minnesota, New York, Pennsylvania, and Wisconsin are up this year and are likely to have the biggest impact, since the difference between a gerrymander and a nonpartisan map in these states has the potential to swing multiple congressional seats in each of them. Furthermore, several of these states have legislative chambers where partisan control or one party’s supermajorities could be at stake depending on the outcome of redistricting.

Below, we’ll examine a few of these states that involve special situations, plus a few states we've excluded from our list because their gubernatorial outcomes won’t or are unlikely to matter:

● Alaska: The governor appoints two of the five members on the state legislative redistricting commission, while the chief justice of the state Supreme Court and the state Senate and state House leaders each appoint one. If independent Gov. Bill Walker or former Democratic Sen. Mark Begich defeats the GOP’s nominee and the Democratic coalition maintains their hold on the state House, the GOP would lack a majority on the commission.

● Arizona: Arizona has an independent commission that handles both congressional and legislative redistricting, but because it was created by a ballot initiative in 2000, Kennedy’s retirement from the court could soon see ballot-initiated commissions struck down as unconstitutional for federal elections if Chief Justice John Roberts gets his way.

● California: Like Arizona, California’s independent commission could also be struck down, but since Democrat Gavin Newsom is an overwhelming favorite to win this year’s gubernatorial election, if the commission is invalidated, Democrats would control redistricting.

● Colorado: Colorado will vote on two ballot measures this fall to create independent redistricting commissions for congressional and legislative districts. Unlike in Arizona or California, these measures were referred to the ballot by the legislature, rather than initiated by the public, and would thus be protected from an adverse Supreme Court ruling.

● Florida: Florida’s next governor will start his or her term with the power to replace three of the four liberal-leaning justices who face mandatory retirement on the seven-member Florida Supreme court. Liberal control over the court was critical for upholding the voter-initiated Fair Districts Amendments, which curtailed the GOP’s most recent gerrymanders. While the U.S. Supreme Court may strike down the congressional Fair Districts Amendment, making a gubernatorial veto the key defense against a gerrymander, Florida’s court could still enforce it for legislative redistricting, where the governor lacks the power to veto.

● Iowa: Iowa has a nonpartisan advisory agency that has drawn congressional and legislative districts since the 1980s, but the agency was created by statute. No party has held unified government in a redistricting year in decades, but if the GOP continues to remain in power, they could repeal the law that established the agency in the first place.

● Maryland: Maryland Democrats are highly unlikely to lose their three-fifths supermajorities needed to override a congressional redistricting veto from GOP Gov. Larry Hogan, who also lacks the power to veto legislative redistricting.

● Massachusetts: Democrats almost certainly won’t lose their decades-old supermajorities needed to override a potential veto from Republican Gov. Charlie Baker.

● New York: New York has a new advisory redistricting commission that still leaves the legislature and governor with power over the maps. Democratic Gov. Andrew Cuomo signed the GOP’s state Senate gerrymander in 2012 and has facilitated their continued control of that chamber, but progressive challenger Cynthia Nixon could block another gerrymander if she defeats him in the Democratic primary. (Whoever wins the primary would be the overwhelming favorite in the general election.)

● North Carolina: North Carolina’s governor lacks the power to veto congressional or legislative redistricting.

● Ohio: Ohio’s governor has the power to veto congressional redistricting if passed by the legislature, while they also sit on the bipartisan redistricting commission that could alternatively pass a congressional map and has sole control over legislative redistricting.

● Oklahoma: Democrats would have to break the GOP’s supermajority in one chamber to uphold a potential veto, but that appears to be a possibility given the massive overperformances Democrats have seen in state legislative special elections since 2016.

● Virginia: Democratic Gov. Ralph Northam could veto a state legislative gerrymander ahead of the 2021 elections, but if Republicans maintain a majority in at least one legislative chamber in 2019, they could delay congressional redistricting until after the 2021 elections in the hopes that they regain the governorship (and the legislature, if they don’t control both houses). In 2011, Republicans, who held the state House and governorship, delayed congressional redistricting until after elections that fall, when Democrats lost control of the state Senate.