Union Pacific is seeking to buy Norfolk Southern in a $85 billion deal that would create the first transcontinental railroad in the U.S, and potentially trigger a final wave of rail mergers across the country.

When Union Pacific and Norfolk Southern announced their merger deal Tuesday to form “America’s first transcontinental railroad,” it puzzled some who recalled the golden spike driven in 1869 at Utah’s Promontory Summit. That last spike only connected two railroads from Omaha, Neb., to Sacramento, Calif.