Nationwide, nearly 3,000 polling places closed between 2012 and 2016. More than 860 of the closings were in seven states, including Alabama, where some or all counties were subject to federal oversight before Shelby.

5. A get-out-the-vote group is hamstrung.

In September 2016, a federal appeals court upheld a 2010 Alabama law that banned money transfers from one political action committee to another.

The stated intent was to guard against corruption, but the law also hurt the state’s largest black political organization: the Alabama Democratic Conference, which works to turn out black voters. Half or more of its revenue used to come from other political entities.

“It’s cut down on money for advertisements, cut down on money on the ground, cut down on money to employ people,” said Joe L. Reed, the A.D.C.’s state chairman. “It’s just a whole lot of things we would do and could do, we can’t do now.”

2017

6. Voter rolls are purged.

In 2017, after mailing postcards to every registered voter, Alabama officials listed more than 340,000 voters as inactive, a precursor to removal from the rolls if they don’t vote in the next four years.

Many states use a similar process to identify voters who have moved, but it can be unreliable. And while inactive voters who show up to the polls are supposed to be allowed to vote normally after verifying their registration details, workers wrongly forced many of them to cast provisional ballots in the U.S. Senate special election, according to the NAACP Legal Defense and Educational Fund.