CHICAGO (AP) — Railway executive Matthew Rose stood before fellow industry leaders, pointing to a map meant to tell the future of the U.S. rail freight network. It was drenched in red — east to west, north to south.

The blotches illustrated areas where, by 2035, traffic jams could be so severe trains would grind to a halt for days with nowhere to go.

"For those of you who've ever seen a good rail meltdown, this is what it looks like," Rose, CEO of Burlington Northern Santa Fe Corp., said as the crowded hall shifted uncomfortably in their chairs. "It's literally chaos in the supply chain."

While the nation's attention is focused on air travel congestion and the high cost of fuel for highway driving, a crisis is developing under the radar for another form of transportation — the freight trains used to deliver many of the goods that keep the U.S. economy humming.

The nation's 140,000-mile network of rails devoted to carrying everything from cars to grain by freight is already groaning under the strain of congestion, with trains forced to stand aside for hours because of one-track rail lines.

And it's probably going to get worse over the next two decades, according to an analysis of government and industry projections by The Associated Press and interviews with experts on rail freight.

The damage to the U.S. economy could climb into the billions of dollars. Higher shipping costs would raise prices for everything from lumber to grain. One analyst said the rail crunch could add thousands of dollars to the price of a car.

"It's not rocket science to see we have a calamity coming down the road," said Paul Bingham, a transportation analyst at research firm Global Insight.

Congestion around the country has remained chronic, even as the ailing economy has led to a 3 percent dip in freight train traffic in the first few months of this year compared with last year. And a new U.S. Chamber of Commerce report warns demand for freight trains is expected to double over the next 25 years.

The problem is that there's no room.

"Even if the estimates are half wrong, we can't put even 25 percent more freight in the system right now without serious implications," said Randy Mullett, an analyst for the nonprofit Transportation Research Board.

Already, delays hamper the existing rail freight network. A lone train stopped in Chicago can force other trains to stop or slow as far away as Los Angeles or Baltimore.

"It's a ripple effect," said Scott Haas, a vice president for United Parcel Service, which uses 3,000 freight cars every day, more than any other U.S. business. "Everything in my system backs up."

Atlanta-based UPS hasn't determined the total cost of freight route congestion, but says that just five minutes of daily delays for each of its drivers amounts to $100 million in company losses a year.

Other modes of transport can't take up the slack: Trucking faces its own congestion problems, a shortage of drivers and high fuel prices. Ships and barges can't reach large parts of the country. Airplanes couldn't begin to carry the millions of tons of coal, waste, chemicals, grain and cars hauled by trains. And hauling freight by rail remains far more fuel-efficient than trucking.