On 13 Sep 1853, Frederick Samuel Dellenbaugh was born to Samuel and Elizabeth Dellenbaugh in the small frontier community of McConnelsville, Ohio. He spent most of his boyhood in the Midwest, but eventually moved with his parents to Buffalo, New York, where he graduated from high school. At Buffalo High School, Dellenbaugh developed those skills and talents that were to land him a seat on John Wesley Powell's second exploratory voyage down the Colorado River. Known locally for his quick hand with a sketching pencil, Dellenbaugh combined his early inclinations as a naturalist with his artistic talent to produce numerous drawings and paintings of upstate New York. In conjunction with his avid interest in boating, these artistic skills made him exactly suited to the expedition's need for a painter to supplement the as yet unpredictable art of photography.

Dellenbaugh's uncle, Almon Harris Thompson introduced him to Powell who quickly appointed him the expedition's artist and assistant topographer. As he was only seventeen years old and a recent graduate, the young adventurer did not feel that his parents would agree to the dangerous trip. So he left at night on a sleeper train for Chicago without telling his mother and father and immediately set to work helping the group with the extensive preparations for the long and dangerous voyage. As they left Chicago for Green River, Wyoming, the jump-off point for the trip, Dellenbaugh finally sent a telegram to his parents.

On 22 May 1871 the party pushed off from Green River City. Unlike the first Powell expedition, Dellenbaugh's group landed frequently to collect botanical samples, take photographs and paint, do surveying, and map the surrounding countryside. The first summer the expedition journeyed past the junction of the Green and Grand Rivers and stopped finally at Lee's Lonely Dell. Powell's group wintered at Kanab, Utah, and busied themselves making a detailed topographic map of the area. Dellenbaugh's personal travels encompassed much of the area surrounding Kanab including the Kaibab Plateau, Hurricane Mesa, Markagunt Plateau overlooking Zion National Park, and the edge of the Grand Canyon near Toroweap Valley.

During the spring and early summer of 1872, Dellenbaugh accompanied Almon Thompson on a reconnaissance northward from Kanab past the White Cliffs, Kaiparowits Peak, Potato Valley, and onto the Escalante River which they discovered, mistaking it for their objective, the Fremont or Dirty Devil River. It was the last major river discovered in the continental United States. From the Escalante they moved east and northward, exploring the Aquarius Plateau and the Henry Mountains before they reached their destination at the junction of Crescent Wash and the Colorado River. There they recovered one of the expedition's lost boats, the , abandoned at that point the year before. According to Herbert E. Gregory, a geologist and authority on the region, Thompson and Dellenbaugh's exploration represented an important achievement. It "made known the agricultural possibilities of the region at the head of the Paria and the Escalante, the remarkable Aquarius and Kaiparowits Plateau, Water Pocket Fold, and the Henry Mountains that formed the basis of the classic works of Dutton and Gilbert."

Eventually, Dellenbaugh returned to Lee's Lonely Dell and 1 August 1872 the final and most dangerous phase of the river exploration began--the traverse of Marble Canyon and the difficult stretches of the Upper Grand Canyon. Powell decided at the end of this fearful stretch of white water that the scientific purposes of the expedition had been served and ended their voyage of discovery at Kanab Creek on 7 September 1872. Under the tutelage of Thompson, Powell's group spent the winter finishing their map of the area and on 16 February 1873, Dellenbaugh arrived in Salt Lake City carrying the various maps prepared by Powell's group.

After spending 1873-1875 in New York, Dellenbaugh traveled for two years by himself exploring the mesas, plateaus, and river valleys of southern Utah, northern Arizona, and Nevada. Leaving Salt Lake in 1875, he rode south to Kanab, then over to Zion's Canyon, following the Virgin River past St. George and down into Arizona and California. In 1876 he made another huge arc through the southwest meandering from Salt Lake, St. George, the North Rim of the Grand Canyon, and Kanab, all the while painting landscapes and Indian life and recording his experiences and observations in his journals. Dellenbaugh began to take himself more seriously as a painter at this point in his life. In 1877 he left the Southwest and journeyed to Munich, Germany, where he studied art for a year at the Royal Academy. Paris was the next stop on Dellenbaugh's artistic pilgrimage through Europe. He sharpened his skills for several years at the Academie Julien under the renowned French painter Auguste Carolus-Duran. During the winter and spring of 1844-1885, Dellenbaugh made what was to be his last trip to the wilds of the Southwest for many years. He lived for six months with the Hopi Indians in the Four Corners area, primarily sketching scenes from village life. The best collection of Dellenbaugh's paintings rests in the Museum of The American Indian in New York.

1885 marked a turning point in Dellenbaugh's life. He returned to New York and married Harriet Rogers Otis, an actress with David Belasco's theatre group. Now settled permanently in New York, Dellenbaugh spent the next fourteen years doing research, writing, and lecturing on his favorite topics, Western exploration, the American Indian, and the Colorado River Basin. He and his wife usually wintered in New York City for the cultural life and spent the summers on the family farm at Cragsmoor, New York, where Dellenbaugh did much of his writing. A complete list of his publications is included in this register's Chronology section.

With the publication in 1908 of his most famous work, , Dellenbaugh became a nationally recognized expert on the history of the Colorado River Basin. Written almost forty years after his trip, Dellenbaugh reconstructed Powell's second exploratory voyage with such immediacy and detail that his book was later awarded the John Burroughs Memorial Association Medal for "The Best Work Relating To Nature." Using his own diary and those of his uncle Almon Thompson and John F. Steward, Dellenbaugh's account stood as the most accurate and readable source of information concerning Powell's work for many years (being reprinted in 1926) until the began publishing the other surviving diaries from the second expedition in 1939. The Yale University Press bought the rights to in 1959 and reprinted it as part of their Western Americana Series.

In 1899, the aging explorer began his last extended bout of extensive traveling by accompanying E. H. Harriman's expedition to Alaska and Siberia. Harriman wanted Dellenbaugh as the group's painter, and he made over sixty-five paintings in oil of the expedition's wanderings, the wildlife, the delicate plant life, and the awesome scenery of the sub-Arctic wilderness. In 1903, Dellenbaugh resumed his personal explorations of the American Southwest, this time making a more complete exploration of Zion's Canyon and the north rim of the Grand Canyon. E. H. Harriman mounted a second sub-Arctic exploration in 1906, this time to Spitzbergen, Norway, and Dellenbaugh was again called upon to use his artistic talents to record the group's adventures and discoveries. Not satisfied with one extended trip in a single year, Dellenbaugh set out for the West Indies in the fall of 1906. From the West Indies he made one last journey on horseback through his beloved Colorado River Basin, working his way along the southern rim of the Grand Canyon and on into California, where this incredible trip ended in 1907.

In his declining years, Dellenbaugh became one of the leading members of a New York group of explorers and naturalists. From 1909-1911 he served as the librarian for the American Geographical Society and in 1922 he helped found the Explorer's Club and served as its first vice-president for six years. Dellenbaugh's last trip to the West was made under somewhat unusual circumstances. In 1929, he was called to testify at the Colorado River Basin litigation between the State of Utah and the Federal government. The question of who owned the riverbed and its minerals hinged on whether the Colorado River was navigable or not. If it was not, the Federal government would own the land. Dellenbaugh testified for the government that, although he had journeyed down the river, it was not navigable in the traditional sense of the word. What impact his testimony had on the final verdict is, of course, impossible to discern, but the case was decided in the government's favor. For a somewhat adulatory account of Dellenbaugh's presence at the trial, see Harold D. Carew, "Wilderness Breaker" ( , November 1929).

During his last trip west, Dellenbaugh revisited southern Utah by auto and the sites of his earlier landmark explorations. While in Utah on this last trip, he made the acquaintances of Dr. Russell Frazier, Charles Kelly, and R. T. Stites. The letters contained in this collection are correspondence between these men and Dellenbaugh and deal primarily with the Colorado River--its history, exploration, and natural wonders. Dellenbaugh died in New York City on 29 January 1935.