Redistricting: Here’s how the new congressional maps shift voting power

The GOP advantage over Democrats has endured even as more states have adopted independent redistricting commissions. Many of the states with redistricting commissions are governed by Democrats or both parties. Just two of the nine states where commissions drew the lines this cycle are controlled by Republicans: Idaho and Montana, which together equal only four congressional districts. Overall, redistricting commissions controlled the map drawing process for 110 districts nationwide, with California’s 52 districts representing nearly half of those.

When the party or parties in charge of the process can’t come to an agreement, or the adopted maps create legal issues, frequently state or federal courts step in instead. Courts have decided the lines in more districts than Democratic state governments. In this cycle, courts have decided the lines for 91 districts — 26 from the state of New York alone.

Both parties had control of the process for 90 districts in 2000. But this time, more than 20 years later, Maine’s two districts were the only two redrawn under both parties’ control.