The infrastructure package puts $66 billion into rail. It could power the biggest expansion in Amtrak’s 50-year history.

The $1.2 trillion bipartisan infrastructure bill that passed the House on Friday is expected to spur the largest expansion in Amtrak’s history while kick-starting repair and replacement projects across the nation’s passenger rail network.

The bill includes $66 billion in new funding for rail to address Amtrak’s repair backlog, improve stations, replace old trains and create a path to modernize the Washington-to-Boston corridor, the nation’s busiest. It would be the biggest boost of federal aid to Amtrak since Congress created it half a century ago.

“It’s transformative,” Amtrak chief executive William J. Flynn said in an interview Monday. Money set aside for Amtrak, he said, “represents more funds than have been cumulatively invested in Amtrak over the first 50 years of our history.”