The railroad business has been heating up, thanks in part to the energy boom underway in parts of the United States. Now there’s word that Canadian Pacific Railway approached U.S. rail company CSX Corporation about a merger. CSX reportedly declined.  

Together the two companies would have a market value of about $62 billion, according to the Wall Street Journal, which first reported the proposed merger. Combined they have more than 35,000 miles of track across much of Canada and the U.S.

The offer comes as the railroad business is experiencing a resurgence, fueled partly by an increase in crude oil production in states like North Dakota and Texas. Major railroads operating in the U.S. made more than $2 billion hauling crude last year, according to the Journal. Meanwhile, bumper crops of grain in the Midwest and Canada and an improving economy have increased other kinds of rail traffic.

“The railroads are suffering right now from basically too much traffic that they’re having a little difficulty handling,” says Steve Ditmeyer, who teaches railway management at Michigan State University. “It’s a problem, but it’s a good problem that they have.”

All the extra traffic has caused delays for Amtrak, the passenger rail service, and for farmers trying to get their products to market.