BOONVILLE, Mo. -- For nearly two decades, the rusted old rail bridge over the Missouri River here stood unused, its massive lift-span suspended permanently in the raised position to allow barges to pass beneath.

The Katy Bridge made a lovely silhouette against a setting sun. But trains no longer rumbled across. Weeds sprouted in rotting rail ties. The bridge's owner, Union Pacific Corp., offered to give it to Boonville, but the town declined because it couldn't afford liability insurance.

Then last year, news leaked that Union Pacific was preparing to destroy part of the Katy Bridge and float the rest down river for use elsewhere. Boonville went bonkers. Now the bridge nobody wanted is the prize in a political tug of war pitting Boonville, pop. 8,200, against Union Pacific, the nation's largest freight railroad.

The little clash is a ripple of larger forces such as China's ravenous appetite for steel, rising U.S. freight volumes and small towns' fondness for using history as an economic tool. At a demonstration May 3 on the courthouse lawn, more than 70 townspeople hoisted handmade signs reading, "Save the Bridge for Our Kids," and "Don't Let Big Business Bully Us." Some vowed to handcuff themselves to the bridge to foil a wrecking crew.

"We're left to defend our little piece of our heritage," says Sarah Gallagher, Boonville's economic-development director. With a motto of "Our Past Is Our Future," the city is home to more than 350 buildings on the National Register of Historic Places. "There are some things you just can't put a dollar figure on," Ms. Gallagher says.

But Union Pacific has put some dollar figures on the 73-year-old bridge that run in the millions. Because of the soaring cost of steel, the Katy Bridge's 3,600 tons of corroded metal are now worth so much that the Omaha, Neb., company can replant the bridge somewhere useful for about half what a new bridge would cost, and at the same time ease a railway bottleneck.

"Is it cooler to have an old bridge on the river? Sure," says Ted Kettlewell, vice president of OCCI Inc., the Fulton, Mo., company that Union Pacific has hired to remove the bridge for $9.8 million. But "it's excellent stewardship of resources for the railroad to reuse it," he says.

Locals call it the Katy because it was built by the Missouri-Kansas-Texas Railroad -- MKT -- in 1932. Railway Age magazine called it "a novel design of electrical lifting and automatic leveling machinery." High above the river, giant gears turned by 80-horsepower motors lifted the bridge's 408-foot-long center span when barges needed to pass.

In 1986, the MKT Railroad stopped using the line that crossed the Katy because the farm economies of central Missouri towns had faltered. A year later, the railroad contracted to give Missouri the right of way to 200 miles of track for $200,000. The deal excluded the Katy Bridge because the state didn't care to insure or maintain it. The railroad agreed to keep the bridge available "for transportation purposes," while the state retained the right to claim the bridge along with liability for accidents, according to the 13-page contract.

"No one wanted it," says Raye Reynolds, a former MKT executive who signed the agreement. "It was a white elephant."

A 1983 federal law allows rail corridors not needed for train service to be banked for future transportation needs while being used in the interim as recreational trails. Missouri turned the MKT land into the Katy Trail State Park, a winding countryside path that attracts hundreds of thousands of bicyclists, hikers and other tourists each year. Because the state didn't own the Katy Bridge, the trail detoured past it to a bridge used by automobiles at Boonville's Main Street.

Union Pacific acquired MKT in 1988. The new owner had little use for the Katy Bridge and offered it to the Boonville Area Chamber of Commerce, says Danielle Blanck, then the chamber's executive director and now Boonville's mayor. She turned it down, assuming that insurance against bridge accidents would cost tens of thousands of dollars. There was occasional talk of sprucing up the bridge as a tourist attraction, but "we had no money," she says. Still, nobody worried about the bridge "because we thought it would be there forever."

Throughout the 1990s, the U.S. Coast Guard goaded Union Pacific to remove the bridge because an unused bridge is considered hazardous to navigation. Union Pacific spokesman Mark Davis says the company tried, without success, to sell it. The bridge stayed.

Then last July, a reporter for the Boonville Daily News was having lunch with a friend who mentioned that her husband had been hired by a company preparing to remove the bridge. Union Pacific confirmed the rumor in the newspaper's front-page story, which said demolition work was imminent.

Thanks to the price of steel, the white elephant suddenly was a golden goose. Mr. Kettlewell, Union Pacific's contractor, estimates the lift-span could fetch more than $100,000 as scrap. The other four spans would be reassembled on the Osage River near the state capital, Jefferson City, where a single-rail bridge now funnels traffic from two lines. Building a new bridge at current steel prices would cost $20 million, Union Pacific estimates. After paying Mr. Kettlewell, the railroad stands to save at least $10 million on the project.

For other reasons, people in Boonville began to see the bridge as a treasure they had taken for granted. Ms. Gallagher, the economic-development official, says it could be a boon to tourism by luring railroad buffs, birdwatchers and history lovers. And it could complement other attractions, including a new steamboat museum under construction and a 100-year-old riverfront hotel due to reopen this year. Boonville now has money, too, from a casino opened at the foot of the bridge in 2001. It fed $4 million into city coffers last year.

Led by Ms. Gallagher and Mayor Blanck, a fledgling group of activists vowed to restore the bridge as part of the hike-and-bike trail. They found a sympathetic ear in Stephen Mahfood, director of the state Department of Natural Resources. In one of his last acts before resigning Dec. 31, he claimed the bridge as state property under the 1987 contract, calling it "a once-in-a-lifetime opportunity" to enhance the Katy Trail and Boonville's economy.

Mr. Kettlewell, the contractor, went to work -- lobbying. By his own description, he's an acquaintance of Missouri Republican Gov. Matt Blunt and an energetic Republican fund-raiser. His company has invested $3 million in a new crane and other gear for the bridge removal. In a meeting and emails with Gov. Blunt's staff, he stressed that, while Boonville's goals were laudable, neither the financially strapped state nor the city could afford the $5 million or more he says is necessary to make the bridge safe for daily foot and bike traffic.

Bridge backers think they can make the bridge usable for about $2 million, but nobody has done a serious cost study. So far, the Save the Bridge Committee has raised a bit more than $10,000 in donations.

Boonville plied Gov. Blunt with emails, letters and phone calls. A congressman, two state senators and a state representative intervened on the city's behalf. But on April 25, the governor's new Department of Natural Resources director said Missouri would cede control of the bridge to Union Pacific "since no viable plan to raise the funds necessary to repair the bridge has been put forward."

Union Pacific is awaiting permits. "We've found a use," the company spokesman says. "That's what we're going to do."

Boonville hasn't given up. After the demonstration, officials met at City Hall to brainstorm ways to keep Union Pacific at bay. Mayor Blanck sat with her dachshund, Heidi, on her lap. As a lawyer drafted yet another letter to the governor, Ms. Blanck said ruefully, "You can tell them the mayor regrets that she didn't take the bridge when it was offered to her."