For 200 million years, up to about 10,000 years ago, land existed between the Stanovoi Highlands of Siberia and Alaska. Across this bridge -- destroyed by the last Ice Age -- animals and men came to America. They wandered southward, along the Rockies, Mexico, and South America. This route is called the Great North Trail. It has played an essential part in the development of this continent and witnessed many of the wildest, most unbelievable-but-true -- as well as most important -- events in American history. Montanan Dan Cushman tells the story of the Great North Trail with excitement and love. He sets the scene by giving -- in thorough and exciting detail -- the geological explanation for the birth of the Trail, its mountains and valleys; and by briskly covering thousands of years of anthropology. Next, Mr. Cushman embarks along the Trail with a fabulous Spaniard, Cabeza de Vaca, and Coronado's 1540 expedition that swept across the Rio del Fuerte, along the Yaqui and Sonora rivers to Zuni and Kansas. Mr. Cushman also recounts the French and English fur trade -- a story full of silent men tracking the beaver through virgin forests -- a story idyllic in its "noble savagery" and barbaric in its result, since it led to some of the ghastliest of Indian wars, those involving the Black-feet. With the 19th century the Great Northern Trail saga becomes one of gold and cattle -- an epic of red-eyed greed and horny-handed brutality -- that Mr. Cushman spins into a memorable yard (of the type he heard out in Montana when he was a boy). Last Chance Gulch springs to life again with its gold dust, bawdy-houses, saloons, and pioneering folk (one of whom, a horse thief, was buried with his gun in one hand, and his playing cards in the other). Billy the Kid and Henry Plummer (who worked both sides of the law at once); Print Olive, the toughest cattleman ever to come up the trail; the Blood Chief Calf Shirt, the booziest Indian of all; "Cattle Kate," the first woman ever lynched (she rustled some, they said); the participants of the Johnson County War -- all reassume their shootin' places on the stage. Mr. Cushman writes with a marvelous feel for the quirks of history: he speaks of a cowboy delicacy called "son-of-a-bitch-in-a-sack"; of Mr. Laumeister's extraordinary camels (whom the Indians called devil elk or stink elk); of how Fort McKenzie was lost for the sake of a pig. And he brings his pungent story down into our century with a great Klondike Gold Rush that crested in 1898 and spilled into the 1900's; the whiskey runners of Prohibition; and finally and much more soberly, the Alcan Highway. Dan Cushman is the author of The Grand and the Glorious; The Silver Mountain; Goodbye, Old Dry; and the Book-of-the-Month club selection Stay Away, Joe.