At a few ticks before four, Mayor Bud Elliott steps up. He lifts a shotgun. (Last year, he switched to a new gun because the old one's tricky hammer nearly took off his thumb, twice.) Bud eyes the clock. Three...two.... The race director shouts a final warning: "If you drop out, you must get your wristband cut off!" Otherwise, they won't know who's still out in the woods. Fewer than half the runners will make it back to Leadville on their feet.

Blam!

"Nothing will happen for the next 10 or 12 hours," a Leadville contestant once wrote of this moment. "Then we will engage the beast." The first miles are heaven. It only takes a few minutes for your body to warm and nerves to settle, and once they do Leadville is the greatest place to be, at the greatest time to be there. When you hit the 10-mile mark, the sun is rising, the snowy peaks are glowing, and Turquoise Lake is living up to its name. It's all so magnificent, you forget it will be late tomorrow morning before you get back.

May Queen Campground is 13 miles in, and as you approach this first aid station you suddenly hear "Whoop-whoop-whoop!" and see men waving six-shooters and women flouncing in gowns and corsets. These are the "Leadville Raiders," a group of locals who like to dress up in old-time gear. "When Ken first came looking for volunteers, it was a real depressing period," says John Cirullo, a Realtor whose business seemed doomed. "But every club in town stepped up, before we even knew the impact the race could have."

"I should've known," Ken acknowledges. "Miners are people of extremes. You tell anyone else you want to run 100 miles, they call you nuts. Tell a miner, he'll ask if you need a hand."

Up and over 11,000-foot Sugarloaf Pass, the racers run on down to the 40-mile mark at Twin Lakes, where Doc Perna and Cindy Corbin, the obstetrics chief, will be stomping their feet for warmth in a dirt-floored garage, as they have every year for 23 years. Doc likes to check everyone out here, before they ford the river and hit Hope Pass, which one runner describes as "a boulder staircase shooting straight up to the sky."

"We've recommended a few people get out of here," Perna says. "A few for chest pains. One guy was coughing blood." The hotels in Leadville are full for race weekend, but so is the emergency room. "The hospital makes a ton of money," Ken happily points out. Since the inaugural race, Leadville has added four more endurance challenges: the Leadville Trail Marathon, the Leadville 10k, the Leadville Trail 100 Mountain Bike Race, and the Leadville Silver Rush 50-Mile Mountain Bike Race, all on separate weekends throughout July and August. Add the Leadville Trail 100 Training Camp in June and the surprisingly competitive burro race during Boom Days in early August, and Leadville's businesses (and paramedics) are humming all summer. The first race drew 45 contestants; now, however, about 450 runners show up at the starting line, with 500 being the cutoff.