Speaking of Lewis and Clark, their official narrative is probably the most collectible of all American travel books. Officially titled Travels to the Source of the Missouri River and Across the American Continent to the Pacific Ocean, it recounts their journey across the Northwest from 1804-1806. However, it was not until 1814 that their official report was published, delayed in part by the mysterious death of Meriwether Lewis. The first American edition of this book is now priced into six figures, but item 138 is the first London, published the same year, but more modestly priced. $35,000.

We are currently celebrating the 200th anniversary of Lewis and Clark's remarkable voyage, and naturally the landscape has changed drastically from what they saw. Here is a midpoint in that change: The Trail of Lewis and Clark, 1804-1904. Olin Wheeler recounts a journey along their route taken at the time of the 100th anniversary, along with a description of the "many changes" that had already occurred. Item 133. $600.

Next is the second most noted American travel of the early 19th century: An Account of Expeditions to the Sources of the Mississippi, and Through the Western Parts of Louisiana...During the Years 1805, 1806 and 1807. This is the account of the Zebulon Pike expedition, which first unsuccessfully sought the source of the Mississippi, and then explored the Southwest, including some harrowing winter days high in the Rocky Mountains. Pike was a military man, and he did not begin to match Lewis and Clark in terms of careful accounting of what they saw and found. His interests were more toward understanding what the Spanish were up to in land that is now part of America, but was then in Mexico. Nevertheless, this was one of America's great expeditions, as the territory was mostly unknown at the time. Item 170. $25,000.

The source of the Mississippi would finally be found in 1832. This expedition was led by Henry Schoolcraft, who had already made several journeys into the far northern reaches of the U.S., and had previously misidentified the source. This time he got it right, though the main purpose of his journey was to negotiate peace among warring Indian tribes. Schoolcraft's book is a Narrative of an Expedition Through the Upper Mississippi to Itasca Lake, the Actual Source of this River... Item 181. $850.

The website for George S. MacManus Company is www.macmanus-rarebooks.com, phone number 610-520-7273.