In 2023, unions added 139,000 members, but the share of the U.S. workforce that's unionized declined from the year before due to even faster growth in nonunion jobs.

The Teamsters union reached a tentative deal with UPS, narrowly averting a nationwide strike. Rank-and-file union members are voting on whether to approve the contract.

Unionized UPS workers voted overwhelmingly to authorize a strike on Friday, setting the stage for a potential work stoppage if the package delivery company and the Teamsters can't come to an agreement on a new contract.

With support for unions at its highest point since 1965, Democrats hope they can capitalize on that sentiment as they struggle to connect with voters on other issues.