U.S. retailers and labor leaders hailed the approval of a six-year longshoremen’s labor contract as a return of stability and certainty to port operations from Boston to Houston.

The approval “is welcomed news to the nation’s retailers, who have been on pins-and-needles for the past year due to the possibility of a supply chain disruption along the 14 East and Gulf Coast container ports,” said Jonathan Gold, vice president for supply chain and customs policy for the National Retail Federation.

The 14,500-member International Longshoremen’s Association, AFL-CIO, approved the contract by an overwhelming margin, which covers operations at 14 ports, the ILA said.

“ILA members won handsome gains in the new six-year agreement, including wage increases totaling $3 an hour spread out over the life of the agreement that will, by the final year of the new contract, bring their hourly rate of pay to $35.00 an hour,” the union said in a statement.

“Lower tiered workers will enjoy an even higher wage percentage increase as their pay progression scale was shortened to six years from nine years in the new agreement. Thus, a new ILA member earning a base pay of $20.00 an hour at the start of the 6-year contract will increase to $35.00 an hour by the end of the sixth year of the contract.”

The last contract, which expired on Sept. 30, 2012, gave longshoremen an average annual salary -- including benefits -- of $124,138.

Members of the United States Maritime Alliance, which represents 43 container carriers, direct employers and port associations, are expected to approve the contract when they vote on April 17.