Some 1,700 miles (2,700 kilometers) later, he's burning through his family's life savings as he collects stories of hardworking, honest everyday people in rural America .
"The scenery in America is changing and I'm really proud we're taking a snapshot at slow motion of this time period, because 20 years from now it will be different," he said.
Inman soaks it all in atop Blackie, a 16-year-old thoroughbred-quarter horse mix who's averaging 20-25 miles (32-40 kilometers) a day along backroads from Oregon to North Carolina.
Inman, 48, started June 2 from his hometown of Lebanon, Oregon, and is halfway through his cross-country trek dubbed Uncovering America by Horseback.
His wife, Brenda, also 48, drives ahead in a pickup and horse trailer filled with water and provisions for Blackie, three dogs and the couple.
They estimate the journey will cost them US$45,000 ( Ђ 30,000). They want to make a documentary film and write a book, and a filmmaker and Web site operator are tagging along.
Said Inman: "It's probably the most stupid thing I've done financially, but I truly believe in it."
He and his crew often rely on strangers since they don't have national sponsors to underwrite them. They'll accept a meal, a place to sleep, cash, or donated feed for Blackie, who eats about 20 pounds (9 kilograms) of high-fat feed a day.
Bill began his trek after growing weary of the daily media drumbeat he thinks is too focused on war, crime, poverty and assorted social ills.
"Unfortunately, the image they are portraying is there's corruption in every politician and there's criminals running everywhere," he said.
Hundreds of interesting people have greeted Inman along the way.
They include a Dodge City man who collects bridle bits, spurs and barbed wire; a Wyoming deputy sheriff who drove 25 miles (40 kilometers) through a rain storm to bring dinner to the Inmans; and a Wyoming woman who gave Bill a pair of stirrups she bought as a Christmas present for her grandson before he was killed in car wreck.
Inman arrived in this rural town with a sweat-stained Stetson and a weathered face that left no doubt ranching has been part of his entire life. The couple rely on media coverage and word-of-mouth to let people know when they reach a new town.
Raised on a Texas ranch, Inman worked cattle, herded wild horses and managed a ranch on an Indian reservation in Nevada before he moved to Oregon last year and began selling horses there. He's also an auctioneer and has done horse-shoeing for nearly 30 years.
Among those meeting Inman on the outskirts of town was Kurly Hebb, former rodeo cowboy and Kansas Cowboy Hall of Fame member.
"He's got my respect. I can tell from talking to him he's going to make it. Just be a cowboy, that's all you got to do," said Hebb, now a rancher.
Joyce Cross met Inman when he came to her restaurant looking for a place to sleep. She found a place for the couple and allowed her 4-year-old son, Kadyn Covey, to ride with Inman the next day.
"The diversity he has unveiled is a lot of forgotten heritage in this country. It's a great eye-opener for anybody who runs into him," she said.
Inman has Oregon , Idaho , Wyoming , Colorado and Kansas behind him. Ahead are Missouri , Tennessee and North Carolina, where he hopes to spend Christmas with his wife's family in Hendersonville .
Inman ticked off a list of what's been bad about the trip - temperatures ranging from 108 degrees (42 Celsius) to freezing, insects, water shortages, crossing mountains and desert, and riding in a lightning storm. People aren't on the list.
"I haven't run into any bad people," he said.