The book "Exploring Expedition to the Highlands, Oregon and California, to which is added a description of the physical geography of California, with the latest information about the gold region from the latest and most authentic sources" is the result of an extremely important journey made by the eminent American explorer John Charles Fremont. In his book, he talks about his impressions of the places he traveled, including the Highlands, Oregon and California, revealing to the reader the uniqueness and beauty of these lands. At the same time, unlike the usual travelogues, the author also adds to his book an in-depth analysis of the physical geographical location of California and provides current and authentic information about the gold deposits, mentioning the most recent sources, which makes this book an extremely valuable source for anyone interested in history and geography of the western territories of the USA.