A narrow majority of Vineyard Transit Authority workers have voted not to join the Amalgamated Transit Union.

All 39 of the company’s eligible voters turned out at the VTA training room at the Martha’s Vineyard Airport on Wednesday to cast their votes. The final vote, cast by secret ballot, was 21 to 18. VTA employees may again seek membership in the ATU in one year.

The Vineyard is just one of three regional transit authorities in the state without union representation. Twelve of the state’s regional transit authorities are members of the ATU, a large labor union that represents workers in the United States and Canada.

Charles Ryan, the president of the local 1548 branch of the ATU, told the Gazette this week that the union began negotiating a contract with VTA employees in 2003, but those negotiations ended when members failed to ratify the contract by a one-year deadline.

“Since then they had like 37 issues that they brought up to the owner of the company and he addressed four of them and dismissed all the rest of them,” Mr. Ryan said. “When you’ve got that many issues it seems like there is a lot of stuff going on that maybe your manager doesn’t want to look at.”

Wednesday’s vote was to determine whether the VTA employees would join the local 1548 branch of the union, which represents Plymouth and Brockton St. Railway Co., Brush Hill Transportation Co. and the Cape Cod Regional Transit Authority.

Some of the issues that have been raised over the years relate to a wage cap of just over $21 per hour and a disciplinary process that some workers say is too rigid.

Mr. Ryan noted that the vote was split down the middle, which didn’t surprise him.

“I always knew that it was a very divided faction of people over there.”