The United Transportation Union has agreed to merge with the Sheet Metal Workers.

The agreement, which followed more than a year of talks by leadership from the two groups, was approved by UTU members Aug. 8. It takes effect Jan. 1. The vote was 71 percent in favor of the move. Under its bylaws, a vote by members of the Sheet Metal Workers was not required. The union’s general executive committee gave its blessing June 13.

The new union will be called the International Association of Sheet Metal, Air, Rail and Transportation Workers, and will be known by the acronym SMART.

Officials estimate the union will have 230,000 members. Sheet Metal Workers general President Mike Sullivan will retain the same position with the new union.

Officials say that SMART will have one of the largest organized labor political-action committees in the United States.