Union Pacific Corporation (NYSE: UNP) and Norfolk Southern Corporation (NYSE: NSC) said the Surface Transportation Board (STB) unanimously rejected requests from merger opponents to dismiss their revised merger application, allowing the regulatory review to proceed.

The two railroads also announced that the International Association of Sheet Metal, Air, Rail and Transportation's Railroad Mechanical Department (SMART-MD) has signed a jobs-for-life agreement with the companies. According to the press release, the agreement means every employee holding a union job at the time of merger approval will retain that job for life. With SMART-MD's support, the merger now has backing from a majority of unions representing employees at both railroads.

"The momentum behind this transaction continues to build, and we are ready to keep moving forward," said Union Pacific CEO Jim Vena. "This merger is all about increasing growth and competition. It's good for our employees, customers and America."

Norfolk Southern President and CEO Mark George said the STB's decision "marks another important step in bringing Union Pacific and Norfolk Southern together," adding that the combination would create new opportunities across merchandise, bulk, and intermodal markets.

According to the companies, the proposed merger would convert 10,000 existing interline lanes to single-line service and add seven new premium intermodal lanes. The companies also claim the combined railroad would remove more than two million truckloads from public highways.

The transaction remains subject to STB review and approval. The two companies expect the deal to close in the second half of 2027.