Michael Petty has read the history and taught it. Now he wants to live it.

The American history professor at Montgomery College is following the footsteps of 19th-century explorers Meriwether Lewis and William Clark to mark the bicentennial of their extraordinary expedition.

From 1804 to 1806, Lewis and Clark blazed a path across the Midwest to the Pacific Ocean, which eventually helped lead to a vast expansion the country's territory. In their honor, a modern breed of history buffs is commemorating America's pioneers by retracing their journey.

Petty, a slim, slightly graying man, has embarked on a personal discovery mission: to bring colorful, coffee-table history books alive as he hikes, bikes, boats and drives across the heartland of America.

"I've maxed out on the reading," Petty said before leaving last week. "Now I want to see the country."

He expects to return Tuesday to his Silver Spring farmhouse after finishing the first leg of Lewis and Clark's route, from Missouri to North Dakota.

"It is a chance to see another beautiful part of America," said Petty, 55. "It is a chance to follow the [Missouri] river, to talk to locals, to hear what they know and don't know about Lewis and Clark."

Petty's ambitious adventure will involve trekking across 1,000 river miles in 10 days, from St. Louis to Bismarck, N.D. -- a voyage that took Lewis and Clark and their 31-member entourage, known as the Corps of Discovery, nearly four months.

An avid hiker who teaches a course at the college on backpacking, Petty's motto is "wilderness is the ultimate teacher." He expects to bring home lessons the history books didn't offer.

"I hope I will have a little empathy with what they went through, which is sacrilegious given how easy it is now," Petty said.

Unlike Lewis and Clark, who traveled by horseback, on foot and in a keelboat, Petty will do most of his traveling by rented car. He began in St. Charles, Mo. -- the original capital of the vast Louisiana Territory -- where Lewis arrived on horseback and met Clark. It is there Petty hopes to see the country's greatest rivers -- the Missouri and the Mississippi -- join together.

"It probably was a pretty exciting site for the Corps of Discovery," he said.

The mighty rivers meet about 10 miles northeast of St. Louis, not far from the cemetery where Clark is buried.

Covering a new city each day, Petty will head to Independence, Mo., where Lewis and Clark's infamous keelboat almost sank. His trip ends in Bismarck, near where the Mandan Native Americans lived and where Lewis and Clark camped for the winter of 1804.

Petty plans to complete Lewis and Clark's entire route next summer, following the path all the way through the mountains of the Northwest to the Pacific Ocean.

The National Park Service has built numerous interpretative signs and plaques along the 3,700-mile historical trail, but Petty will have his eye trained for undocumented spots. "I'm hoping to see a lot of the unheralded places, too," he said.

Petty is traveling alone, leaving behind his wife, "American Girl" series author Valerie Tripp, and daughter Katherine, 16. But he expects to find a few fellow vagabonds and history buffs, hoping to re-create a living history of America's most celebrated adventurers.

A New Mexico State University at Carlsbad professor plans to guide students on a two-week trip along the Lewis and Clark trail. And the Discovery Expedition of St. Charles, Mo., about 25 miles north of St. Louis, leads bicentennial treks along the trail.

Petty is well trained for his trip. He hiked more than 2,000 miles of the Appalachian Trail in 1981, regularly hikes the C&O Canal, and explores other trails around Maryland and Virginia.

Last summer, he took off on a road trip after reading "Blue Highways," William Least Heat-Moon's account of a journey across back roads and byways that had been e marked in blue on old maps. Petty drove across Route 50 from Ocean City to Sacramento for a two-week adventure.

"It's in my blood," Petty said. "It's the Jack Kerouac, Woody Guthrie in me."

Michael Petty, a professor of American history at Montgomery College, will return Tuesday from a journey mirroring the first leg of Lewis and Clark's legendary expedition. An old map, below, shows the explorers' route.