For the first time, UPS Freight Teamsters have rejected the contract negotiated on their behalf by union leaders, the union announced.
The vote was 4,244 against and 1,897 for the tentative contract deal, according to a tabulation posted on the Teamsters website. The current contract expires July 31.
UPS and the Teamsters reached a tentative five-year deal in April for the company's freight and package divisions.
The UPS Freight agreement covers more than 12,000 workers at the less-than-truckload unit and offers a $2.50 total wage increase over a five-year span starting Aug. 1. Neither the company nor the union commented on the vote.
The last contract rejection at UPS occurred in 1997 when the Independent Pilots' Association turned down a contract offer.
It was the second contract ever negotiated between UPS Freight and the union. The initial contract was approved in 2008 after workers voted to become union members. UPS acquired its LTL unit through the 2005 purchase of Overnite Corp.
Votes that were cast on the far larger contract between Teamsters who work in UPS' package division still are being counted. Tabulations on the union's website through June 24 show the master contract is being approved by a margin of about 4 to 3.
Some side agreements to the master package contract, known as riders and supplements, were on pace toward approval, while others were pointing toward rejection.
The package contract covers about 238,000 full- and part-time workers. Its wage package was $3.90 in total over the same five-year period as the freight agreement.