The merger would create the United States’ first coast-to-coast rail network, spanning 50,000 miles and 43 states.

The proposed merger, announced Tuesday, would marry Union Pacific’s rail network in the West with Norfolk Southern’s rails that snake across Eastern states.

Union Pacific has agreed to acquire Norfolk Southern in an $85 billion deal, creating a transcontinental railroad and the largest in the U.S., the companies announced. Why it matters: The railroad megamerger requires regulatory authorization and could push other competitors BNSF and CSX into a deal of their own.