Consistent and timely delivery remains scattershot as the agency struggles to right operations after the rollout, then suspension, of a major midsummer restructuring. In 17 postal districts representing 10 battleground states and 151 electoral votes, first-class mail is on time 83.9 percent; that’s 7.8 percentage points lower than January and nearly 2 percentage points below the national average. By that measure, more than 1 in 6 mailings arrive outside the agency’s one- to three-day delivery window.

The slowdowns, which have raised alarms and suspicions among voters, postal workers and voting experts, have particular implications for states with strict voter deadlines. Michigan, Wisconsin and Georgia, for example, do not accept ballots that arrive after Election Day regardless of postmark. Of the states that do, there is generally a short qualifying window: In North Carolina, where polls have President Trump and Democratic nominee Joe Biden in a dead heat, postmarked ballots must arrive within three days of the election…

In Detroit, where Democrats are relying on heavy turnout to carry the rest of Michigan, only 70.9 percent of first-class mail was on time the week that ended Oct. 9, compared with 92.2 percent at the start of the year.