An American watchmaking tradition is ending.

Timex Corp., the best-selling watch brand in America, is closing its last manufacturing plant, in Little Rock, Ark., after 56 years of operation.

The Middlebury, Conn., firm was the last major domestic watchmaker of the once-thriving U.S. watch industry doing any manufacturing here at all. Over the past half century, other major companies have closed, were bought out, or moved abroad (mainly to southeast Asia), although a few still do some assembly in the U.S. Virgin Islands or Puerto Rico. Timex itself set up assembly operations in the Philippines a number of years ago.

Until last year, Timex’s Little Rock factory, the last U.S. plant to make parts for a widely sold watch brand, made cases and watch parts for 22 million watches, about 80% of Timex’s annual production. The parts were then shipped to Timex’s watch assembly facilities in the Philippines.

The closing, which will affect the plant’s 85 remaining workers, is being done for reasons of cost and competitiveness, say company officials.

“It’s all about efficiencies,” says Jim Katz, public relations manager for Timex. “We have a large watchmaking facility in the Philippines that can take over these tasks and do them more efficiently. They are already doing the bulk of the work.”

Last August, Timex announced it would stop making die-cast watch cases in Little Rock within a year and buy materials from vendors to make die-cast watch cases in the Philippines. Late last year, Timex also closed its Shelton, Conn., distribution center and moved those operations to North Little Rock, where its watch repair center is located. That center, which employs 175 people, will continue operating.

Timex does about $600 million in sales annually and controls about a third of the U.S. watch market in terms of units sold.