The Mill Mountain Zoo officially unveiled the teeny new train that circles its grounds Tuesday morning. It had a sharp paint job and a new name, the Norfolk Southern Zoo Choo -- the name tied to one of the largest corporate sponsorships in the zoo's history.

The railroad gave the zoo $100,000 to help pay for the first train it has owned outright, opening a spigot of new revenue for the nonprofit animal park. In turn, "Norfolk Southern" was applied to one of the smaller locomotives to bear the name.

"We have some model trains," said Wick Moorman, NS' chief executive officer, shortly before taking the Zoo Choo on a celebratory lap. "This is probably the smallest one a person can get on."

But that small train has big money potential, explained Sara Brooks, president of the zoo board.

The Mill Mountain Zoo has operated a children's train since 1952, but never owned it. While $2 rides have raised about $60,000 annually in recent years, the zoo collected only about a third of that after paying upkeep costs and splitting the profits with the previous Zoo Choo's owner, the Roanoke Jaycees, Brooks said.

NS' donation helped cover a large portion of the new train's $70,000 price tag, paid for a coat of Tuscan red paint and left enough for maintenance and operating costs for the next four years.

New Zoo Choo revenue, an anticipated $40,000 extra a year, will go toward the zoo's operating costs, including animal feed and veterinarian bills, Brooks said. And with attendance up about 15 percent this year, she hoped for bigger payoffs from the depot, now named Norfolk Southern Station.

Dave Orndorff, the zoo's executive director, called these corporate sponsorships standard to the business. And when a zoo finds a donor for a new exhibit or upgrade, it usually means a new title, too.

"We'll name it anything they want," Orndorff said.

The new Norfolk Southern Zoo Choo, which started running in May, includes an engine and three passenger cars. As part of Tuesday's celebration, it carried zoo supporters, board members and NS brass, along with several children, on several rounds.

The Roanoke Jaycees moved the old Zoo Choo to the Virginia Museum of Transportation in December.

The new train arrives as the zoo is experiencing an upswing after some hard, lean years on the mountain. The menagerie includes a substantially larger bird collection this year and the zoo is considering a 2-acre expansion to add exhibit space.

"We are doing the best we have done since government funding to the zoo was curtailed" in the late 1990s, Brooks said.