ST. LOUIS • One day last month, a massive green locomotive and a string of railcars rolled out of the Anheuser-Busch brewery, passing the black iron gates and red brick buildings. The train was loaded with beer. It lumbered over heavy steel rails running along the St. Louis riverfront and across a bridge over the Mississippi River.

And with that, the 124-year run of "the beer railroad" was over.

A-B recently informed federal railroad regulators that it wants to shut down Manufacturers Railway Company, the rail company that has been part of A-B since 1887, when A-B co-founder Adolphus Busch turned to trains to supply his growing brewery.

The company is a shortline railroad, operating 13.5 miles of track and providing service only between the brewery and other railroads just over the river in Illinois.

The brewer told regulators that running the railroad "has become highly unprofitable," losing $700,000 last year and with a projected loss of $1.4 million this year. A-B has increasingly turned to trucks for shipping. Also, outside businesses, such as a brick salvager and a box maker, have stopped using A-B's rail service, the company said.

A-B said it would contract with other railroads to bring in supplies for making beer, as it does at its 11 other U.S. breweries. In St. Louis, trains bring in an average of six carloads of grain, celite and magnesite each day.

But the days of trains carrying out beer are gone, the brewer said. The last beer shipment by rail occurred on March 13.

"It's an end of an era," said Gregg Ames, curator of the John W. Barriger III National Railroad Library at the University of Missouri-St. Louis.

Yet the overall railroad industry is booming, Ames said, noting investor Warren Buffett's decision last year to pay $26.4 billion for Burlington Northern Santa Fe, the nation's second-largest rail carrier.

A-B's railroad is known as the MRS, an abbreviation of its former name. The initials are still painted on its green locomotives. The line was a favorite of railroad enthusiasts because of its long history and role in handling beer. The MRS railyard sits across Broadway, opposite the brewery.

In the early 1900s, the MRS shipped not only beer but other items produced along the St. Louis riverfront, from bags to boilers to bathtubs, according to a MRS corporate history in the Barriger library collection.

In the 1940s, the MRS maintained 42 miles of track. A favorite company saying was: "Compare us to any railroad in the world. We're not as long, but we're just as wide." (A reference to its standard-gauge track.)

A-B needs approval of the U.S. Surface Transportation Board to close the railroad, which employs 37 workers. The board decides whether there will be "a serious, adverse impact" to local development from the closure.

A-B's application to the board emphasizes the limited impact of the railroad's closure, because the brewer is its only customer.