One created an international relief agency modeled in no small part on the United Nations. Another produced a mnemonic landscape of expanding and receding subjects, inviting the viewer to navigate the amorphous waters of memory. Still a third illustrated two profoundly violent scenes from Stanley Kubrick’s A Clockwork Orange, playing with the relationship between viewers and viewed.

But no matter how great the thematic differences between the winners of the Great Rivers Biennial 2008, Corey Escoto, Michelle Oosterbaan and Juan William Chávez share one thing in common: Each is profoundly rooted in drawing.

“Their practices are so varied. They’re each interested in very different issues and their relationship to drawing is very different as well,” says Laura Fried, the new assistant curator at the Contemporary Art Museum St. Louis. “But all three are serious draftsmen. Hopefully visitors will draw their own connections.”

Jointly sponsored by the Contemporary and the Gateway Foundation, the Great Rivers Biennial was formed in 2004 with the hope of exposing promising local artists to the broader art world, and, by the same token, exposing the broader art world to the promising artists of St. Louis. Now in its third exhibition, the biennial — this year judged by Cheryl Brutvan (curator of contemporary art at the Museum of Fine Arts in Boston), Lilian Tone (an assistant curator at the Museum of Modern Art in New York) and Heidi Zuckerman Jacobson (director and chief curator of the Aspen Art Museum) — has quickly become the region’s most important juried exhibition. With increased importance has come deeper pockets: This year’s winners will receive $20,000 apiece, up from $15,000 in 2006.

“The best thing a contemporary art museum can do for its local artists is to show them and give them money,” says Paul Ha, the Contemporary’s director. “Our goal is to get [the prize money] to where an artist can actually leave their job for a year.”

In years past the biennial has featured everything from a speaker-studded Chevy Blazer to oil paintings to installations, and while this year’s artists all call upon their shared foundation of drawing, they’ve each placed draftsmanship in the service of another medium.

Michelle Oosterbaan

Originally working as an installation artist whose works — colorful, geometric, inspired by modernist architecture — created the impression of distinct spaces within spaces, Michelle Oosterbaan made the jump to figurative drawing three years back.

“I wanted to slow down,” says Oosterbaan, a visiting assistant professor at Wash. U.’s School of Art. “I enjoyed the fact that I could transform places quickly, but in the end I wanted to make a more beautiful surface. I wanted to spend more time developing something with more of a sensitive touch.”

The result is a series of drawings that takes personal memory — its conflicting distortions, obsessions and vagaries — and seeks to reproduce it on the page. By turns highly detailed and merely gestural, outsize in scale or minute, rendered in bold strokes or the faintest shadow, Oosterbaan’s richly layered drawings seek to mimic the nonlinear and evolving nature of memory: Depending on where you stand, past events will either loom large or retreat into darkness.

“A lot of these drawings are about place or memories of places and creating a sense of myth or story based on memory and little moments in time,” Oosterbaan says. “I’m trying to catch all of them — the big picture, the macro idea — and then the smaller bits inside of that. I’m fascinated by how big events are made out of really small things.”

Many of her drawings, punctuated by large “breathing” spaces of pure, unvarnished paper, feature expertly rendered animals — bears, large cats, dogs — that inhabit metamorphic spaces leading to a hint of water, fences, flowers or layers of earth.

Oosterbaan now works in figurative drawing, but her show also includes installed elements: a stenciled chalk-dust carpet Oosterbaan has created on-site and an “environment” she constructed in the Contemporary’s windows of overlapping colored wax paper that, she says, is an “attempt to really surround the viewer and have them inhabit a place.”

Her past as an installation artist is everywhere on display here, even in her choice of large sheets of paper. Though painterly in size, they’re then populated with intricately rendered and often minute subjects.

“I have to think: What’s worth drawing? Every day we’re bombarded with images, and I need to sit down and think: How does it fit into the ecology of the drawing?” says Oosterbaan. “By pulling the spectator closer, that gets them to participate in the story. These drawings have very particular associations for me, and I don’t anticipate that people will come away with the same story that I’m presenting. It’s more interesting to me to keep it open-ended.”