Union workers who load grain at U.S. West Coast terminals will return to work on Wednesday after ratifying a four-year contract that included work rule changes and wage increases, the union said on Tuesday. The contract between the International Longshore and Warehouse Union and three grain companies that ship wheat, corn and soybeans out of the Pacific Northwest - Mitsui’s United Grain Corp, Louis Dreyfus and Marubeni’s Columbia Grain - ends a two year long dispute. There were also port lockouts at Portland’s Columbia Grain and Vancouver’s United Grain facilities. Grain shipments out of the largest West Coast terminal at the Port of Vancouver, Washington, owned by United Grain had backed up this summer when state officials stopped inspecting grain. The state government withdrew police protection for inspectors to cross the union’s picket line on July 7. About a quarter of all U.S. grain exports are shipped out of the Pacific Northwest, second only to the Gulf of Mexico. The union and the grain handlers had reached a tentative agreement on Aug. 12.