Three tubs of absentee ballots that never reached voters were discovered in a postal center outside Milwaukee. At least 9,000 absentee ballots requested by voters were never sent, and others recorded as sent were never received. Even when voters did return their completed ballots in the mail, thousands were postmarked too late to count — or not at all.

Cracks in Wisconsin’s vote-by-mail operation are now emerging after the state’s scramble to expand that effort on the fly for voters who feared going to the polls in Tuesday’s elections. The takeaways — that the election network and the Postal Service were pushed to the brink of their capabilities, and that mistakes were clearly made — are instructive for other states if they choose to broaden vote-by-mail methods without sufficient time, money and planning.

More than 860,000 completed absentee ballots had been returned by Tuesday, already a record for Wisconsin spring elections. But for thousands of other voters, who never received their ballots, there was only one recourse: putting their health at risk and defying a stay-at-home order to vote in person during the coronavirus pandemic. Many chose not to show up.

Federal health officials have suggested that expanding voting by mail could help reduce crowds at polling places and therefore make elections safer amid the outbreak. The issues that have arisen in Wisconsin offer a warning for other states of the potential pitfalls of a rapid, last-minute expansion of absentee balloting, particularly one marred by a flurry of court challenges and 11th-hour rulings that created confusion and chaos.