GRAND FORKS, N.D. (AP) — Union workers in North Dakota, Minnesota and Iowa who have been locked out of their jobs for 20 months at American Crystal Sugar Co. have voted to ratify the company's proposed contract.

Fifty-five percent voted to accept the contract offer. It was the workers' fifth time voting on the contract.

Employees last voted on the contract in December, when 55 percent voted to reject the offer.

Nearly 1,300 employees were locked out on Aug. 1, 2011, after rejecting the cooperative's proposed contract. Company officials say many of those workers retired or resigned.

The union originally focused its complaints on contract provisions regarding seniority and job security. The company says it's a good contract with substantial increases in wages and other benefits.

American Crystal is the country's largest sugar beet processor.