Less than three months before a presidential election reliant on voting-by-mail, the U.S. Postal Service's own data shows slow mail delivery in regions that include critical battleground states. Postal performance data analyzed by APM Reports shows that the postal districts serving some large cities in swing states failed to meet the government's on-time targets for first-class mail, the class of mail widely used to mail out absentee ballots. Mail delivery around Milwaukee and Detroit has been especially poor, where postal performance has missed targets repeatedly and fallen below the national average since the end of 2016. These charts show the percent-on-time scores for the overnight and two-day service standards, which reflect the postal service's expected delivery time for mail sent within the same city or county. The scores reveal consistently slow mail delivery in some areas, which could create problems for the November election. Read the full story on postal performance and by-mail voting.