Lourie completed his trip. It took him three weeks and marked the first time anyone has traveled from the source of the Hudson to the mouth in a single vessel. The Hudson proved to be a very changeable river. It includes seven locks and nine power dams. The northern half is a true river with strong current, but the lower half is tidal, a sunken river from the days of glaciers. In its first 165 miles, it drops more than 4,000 feet to Albany. The second half falls no more than a foot. Lourie's account of his trip is a fresh look at one of America's great and complex waterways, one of the few, in fact, that still contains its historical and biological species of fish. It is also the longest inland estuary in the world. Henry Hudson called it the "great river of the mountains." Nowadays, too often the Hudson is stereotyped as a ruined, polluted industrial river. its glorious past is compared to its present neglect. In River of Mountains, Peter Lourie combines the Hudson's rich history and descriptions of some of the region's most impressive landscape with the residents of its mill towns, the loggers, commercial fishermen, and barge pilots - all of whom are proof that the river is still a thriving, vital waterway.