Known to Montana First Citizens for millennia, the Gallatin Valley first entered written records when William Clark explored it in July 1806 and called it an open level plain as he crossed eastward into the Yellowstone River valley over what is now Bozeman Pass on July 15th. His account of many beaver dams drew British and American fur trappers, and in 1810 William Ashley established Three Forks Post near here. Jim Bridger also knew the valley, and the mountain range to the east bears his name. Rich gold placers on Grasshopper Creek, Alder Gulch, and Last Chance Gulch in the early 1860s brought thousands of European-Americans to southwestern Montana, and the Gallatin Valley's central location near the gold camps and its fertile soil made it the breadbasket of Montana Territory. Farmers and ranchers sold their products in Bannack and the camps along Alder Gulch, while Bozeman, Belgrade, Manhattan, and Three Forks became important agricultural communities. The arrival of the Northern Pacific Railway in 1883 opened national markets for the valley's wheat, barley, and cattle, and agriculture remains important in the Garden Spot of Montana. A few months after gold was discovered on Grasshopper Creek, 115 miles south, Missouri speculators envisioned near the Missouri headwaters a rich agricultural center and steamboat port, and the Gallatin Town Company platted Gallatin City on the west side of the Jefferson River a little over four miles east of here. Promoters drew settlers from the mining camps and the Minnesota-Montana Road, and small log cabins were followed by a flour mill, a ditch from the Madison River to power it, and a series of river bridges built by James Shedd. At its height in 1866, Gallatin City had a church, school, stores, and post office, and it served as the first county seat of Gallatin County. But the hoped-for San Francisco of a Northern Eldorado never appeared: the Great Falls of the Missouri blocked steamboat traffic, the headwaters area proved poor for farming and unattractive to settlers, people left in large numbers while Bozeman prospered, and by 1870 the county seat had moved to Bozeman and only 160 people remained in the area, leaving Gallatin City a failed dream marked by abandoned buildings and collapsed log cabins.