The task of drawing new boundaries for thousands of federal and state legislative districts is still about three years away, yet the political battle over redistricting already is playing out in this year's midterm elections.
North Carolina's congressional elections were thrown into a week of uncertainty when a federal judicial panel raised the possibility that it would order new districts before the fall elections to correct what it had ruled was unconstitutional partisan gerrymandering. It opted against doing that on Tuesday, conceding there was not enough time.
In Colorado, Michigan, Missouri and Utah, campaigns are underway for November ballot initiatives that would change the redistricting process so it's less partisan and creates more competitive districts. National Democratic and Republican groups are pouring millions of dollars into state races seeking to ensure they have officeholders in position to influence the next round of redistricting.
The results from the 2020 Census are to be delivered to states in spring 2021, triggering a mandatory once-a-decade redistricting for U.S. House and state legislative seats to account for population changes. How those districts get drawn can help determine which party controls those chambers for years to come.
Current political boundaries are being legally challenged in about a dozen states, on claims of political or racial gerrymandering. The lawsuits seek to force districts to be temporarily redrawn for the 2020 elections and, more importantly, establish legal precedents to be followed during the next census-based redistricting.
A lawsuit in North Carolina appears to hold the greatest potential for change. A federal judicial panel has ruled that 12 of the state's 13 congressional districts violate the U.S. Constitution because Republican state lawmakers drew them to their own party's benefit while infringing on the rights of Democratic voters. The case is likely to be appealed to the U.S. Supreme Court, which thus far has shied away from setting a standard for determining when partisan gerrymandering becomes unconstitutional.
Critics of partisan gerrymandering point to North Carolina to illustrate why they believe the process is unfair and disenfranchises voters of the other party. Democrats account for the greatest number of registered voters in the state and hold the governor's office, while registered Republicans and independents are equally divided. Yet the state's delegation to the U.S. House is 10 Republicans and 3 Democrat thanks partly to the congressional lines drawn by GOP lawmakers to maximize their advantage.
A similar partisan gerrymandering claim remains pending against the Wisconsin state Assembly districts after the nation's highest court in June directed the case back to a lower court for more proceedings.
Pennsylvania's congressional districts were redrawn earlier this year after the state Supreme Court ruled that the Republican-drawn boundaries amounted to an unconstitutional partisan gerrymander. Candidates are running under the new map in the November election, with Democrats hoping to cut into what had been a roughly 2-to-1 seat advantage for Republicans in a state where Democrats have a slight registration advantage over Republicans and have dominated statewide elections. A majority of the Supreme Court justices were elected as Democrats.
Voters in several states will be deciding whether to change the criteria or methods by which districts are drawn with the goal of making the process less partisan.
Initiatives in Michigan and Missouri have come under fire by Republicans because the efforts have been led by Democratic activists, although the measures also have drawn some bipartisan support.
The Michigan initiative would strip the Legislature and governor — both currently led by Republicans — of their redistricting duties and instead entrust that to a 13-member citizens' commission that would be prohibited from producing maps providing a disproportionate advantage to any political party.
The Missouri measure, which is facing a court challenge from Republican-aligned attorneys, would affect only state House and Senate seats, not those for Congress. It would diminish the power of the existing bipartisan redistricting commissioners by creating a new position of state demographer who would submit maps designed to achieve "partisan fairness" and "competitiveness."
Utah's initiative would create a commission to propose U.S. House and state legislative districts. A pair of Colorado constitutional amendments, placed on the ballot by the Legislature, would direct nonpartisan legislative staff to submit proposed maps to a 12-person commission with a goal to "maximize the number of politically competitive districts."
In May, Ohio voters overwhelmingly approved a ballot measure altering the state's congressional redistricting process by requiring support from both the majority and minority parties to enact maps that would be valid for a full decade. If the party that controls the Legislature approves a map by a traditional majority vote, it could remain in effect for just four years.
The recent focus on redistricting has been driven partly by the emergence of new statistical calculations to try to gauge the extent of partisan gerrymandering.
One of those new measurements, developed since the last round of redistricting, is called the "efficiency gap." It uses the average share of the vote by which candidates win and lose races to measure the advantage that one political party holds over another in translating its votes to victories.
When The Associated Press ran a version of the efficiency gap formula last year, it found that Republicans won as many as 22 additional U.S. House seats in the 2016 elections over what would have been expected based on the average vote share in congressional districts across the country. It also found far more states with Republican-skewed state House or Assembly districts than Democratic ones.
The Brennan Center for Justice at the New York University School of Law used three statistical tests to analyze the 2012-2016 congressional elections. Its 2017 report found a persistent Republican advantage related to "aggressive gerrymandering."
Experts note that at least part of the Republican advantage is due to geography. Because Democrats tend to be highly concentrated in urban areas in some states, they end up winning some districts by large margins but claim fewer overall districts than geographically dispersed Republicans.