EVANSVILLE, Ind. (AP) _ Salespeople know. So do truckers, cabbies, couriers and pizza deliverers.

Anyone who spends a lot of time on the road must know the disposable drinking cups used by restaurants and convenience stores keep getting bigger and bigger and bigger.

For years, the largest such cups held a mere 16 ounces. Then along came the 24-ounce and 32-ounce cups, followed by vat-like vessels holding 44 ounces and 64 ounces. In Las Vegas, some businesses have even tried out an 85-ounce cup _ roughly two-thirds of a gallon of ice and beverage.

Who's behind this madness? George Willbrandt, vice president of sales and marketing of the drinking cup division of Evansville-based Berry Plastics Corp. He invented the giant, wide-barreled, narrow-bottomed, plastic cup known in the industry simply as the ``drive-thru.''

``We're constantly trying to improve on the total package of the cup and the lid,'' he said.

Willbrandt is the founder of Sterling Products Inc., a maker of plastic promotional drinking cups. When Berry purchased the company in 1995, Willbrandt joined the firm to direct the drinking cup division.

The acquisition turned Berry from a bit player into the industry leader in the injection-molded plastic drinking cup business. Berry's annual domestic cup sales climbed from $7.5 million in 1995 to $40 million last year, when it captured 40 percent of the $100 million market.

Berry has 2,400 employees and now produces about 500 million drinking cups each year at plants in Evansville; Lawrence, Kan.; and Henderson, Nev.

The cups come in 30 different styles. Twenty-six in-house artists and graphic designers make them look any way a customer desires.

Those customers include McDonald's, Burger King, Steak 'n Shake, Cracker Barrel, Bigfoot and Circle K convenience stores, and oil companies Amoco, Mobil, and Sunoco. Berry also provides promotional drinking cups used by college and professional sports teams and its cups can be found at national parks and the Kennedy Space Center.

``It's never the same thing from day to day,'' said Mark LaRue, product line supervisor of the drinking cup division. ``You're dealing with a wide variety of customers and needs.''

Besides drinking cups, Berry's sales are focused in four major product lines: caps for aerosol cans, open-top containers, housewares and lawn and garden products and custom molding.

Berry originally was founded as Imperial Plastics in 1967 and has grown into a large manufacturer of injection-molded plastic packaging. The company was renamed Berry Plastics in 1983, when it was purchased by Jack Berry Sr., a Florida-based citrus grower and real estate developer.

In 1990, the company's assets were purchased by an investment fund managed by First Atlantic Capital Ltd. of New York. Berry Plastics' management owns part of the company.

Acquisitions have been key to the company's success with drinking cups, said Don Loepp, managing editor of Plastics News, a weekly industry newspaper based in Akron, Ohio.

``They put together a group of acquisitions with the right geographical mix for their customers and also the right mix of services and products for their customers,'' Loepp said.

Berry also has deftly adjusted its product mix in recent years as consumer demands declined for certain plastic products, such as caps for aerosol cans, he said.

Willbrandt said that with innovation, manufacturing efficiency, aggressive marketing and customer service, Berry's share the of plastic drinking cup market will keep growing.

``You put all these together, it's what has made us successful,'' he said.