A landmark 1884 atlas of 16 thematic maps depicting the forest cover of the United States and Canada, compiled by renowned Harvard botanist Charles Sprague Sargent and overseen by pioneering mapmaker Henry Gannett.
The atlas was issued, not by the Department of Agriculture, but by the Census Office of the Department of the Interior. A decade earlier the Census Office had gone big-time into thematic mapping, using the Ninth Census (1870) to compile the monumental Statistical Atlas of the United States (1874). The Atlas included a single map of tree cover, “Distribution of Woodland within the Territory of the United States”, which attempted only to depict “five degrees of [woodland] density” across the country, with no attempt to distinguish the distribution of species.
The Tenth Census (1880) took the mapping effort to a new level, one result of which was this remarkable portfolio of 16 large-folio lithographic thematic maps printed in colors. Together they represented by far the most thorough attempt to date to depict the overall tree cover of the United States and Canada and the range of its predominant tree species (For reasons not known, Mexico was not included in the survey.)
The atlas employes two different base maps, one vertically oriented and depicting essentially the entire North American landmass; the other oriented horitzontally and depicting just the United States. On both base maps the states (but not the Canadian provinces) are shown in outline and named, major river systems are delineated in black, and mountain ranges are shown by sepia hachuring. For each of the 16 maps in the atlas, the choice of format depends on the range of the tree species in question. So for example the map treating the Ashes is on the vertical, continental format, while that showing Hickories and California Laurel used the horizontal, U.S.-only format.
The treatment of the thematic data is simple in the extreme: on each map different color shades are used to distinguish different types of tree cover. For example Map No. 1 uses different shadings to differentiate predominantly coniferous forests (dark green), deciduous forests (green-blue), prairies (light blue) and treeless plains (white). Map No. 3 uses five shades of green to distinguish the ranges of five species within the genus Fraxinus (the Ashes). Map No. 6 uses no fewer than eight shades of green to distinguish the ranges of different specis of the genus Quercus (the Oaks). Map No. 7, it is worth noting, depicts the Chestnuts, including the range of the American Chestnut, which species was soon devastated by a blight in the first half of the 20th century.
The overall design of the maps is simple and immediately comprehensible, but I see at least two significant flaws. First, on some of the maps (such as No. 6, showing the Oaks), the color shades are so similar as to make differentiating the species rather difficult. The mapmakers compensated for this somewhat by adding roman numerals keyed to the map legend, but this would seem to defeat the whole point of employing color in the first place. The second flaw is that the use of color to differentiate species obscures the biodiversity of American forests. For example, in Southampton, Massachusetts, where I live and work, one one of my local walks I encounter at least three species of Oak (red, white, and one I haven’t quite figured out). The use of color to indicate species makes it impossible for the map to portray this complexity.
Charles Sprague Sargent and Henry Gannett
Map compiler Sargent (1841-1927) was born to a prominent Boston family, graduated from Harvard in 1862, and served the Union for three years in the Civil War. Emerging unscathed, he traveled in Europe for a time before taking over management of the extensive gardens at his family’s Brookline estate. Mysteriously, given his lack of obvious qualifications, he was in 1873 appointed director of the Harvard Botanical Garden and the new Arnold Arboretum in nearby Jamaica Plain, then under Harvard supervision. Nevertheless he was wildly successful in the position and went on to supervise the Arboretum for more than a half century. He became America’s leading dendrologist (i.e., tree expert), perhaps best remembered for his The Silva of North America (1891-1902) and Manual of the Trees of North America (1905). He participated in a number of plant-collecting expeditions, both domestically and abroad, and was also a prominent conservationist, both of which activities brought him into close collaboration with John Muir.
Sargent and Muir traveled together extensively, including a round-the-world trip in 1903. I stumbled on an anecdote that I imagine captures well the personalities of and relationship between the two men:
“Muir tells this anecdote, about a trip with Sargent to Grandfather Mountain, North Carolina, when Muir became enraptured by the spectacular view of autumn colors from the top of the mountain: “I couldn’t hold in, and began to jump about and sing and glory in it all. Then I happened to look around and catch sight of Sargent, standing there as cool as a rock, with a half-amused look on his face at me, but never saying a word. ‘Why don’t you let yourself out at a sight like that’ I asked. ‘I don’t wear my heart upon my sleeve,’ he retorted. ‘Who cares where you wear your little heart, man,’ I cried. ‘There you stand in the face of all Heaven come down to earth, like a critic of the universe, as if to say, ‘Come, Nature, bring on the best you have. I’m from BOSTON!’” (“Charles Sprague Sargent 1841-1927” on the Sierra Club web site)
A native of Bath, Maine, Henry Gannett (1846-1914) received a B.S. in science from Harvard in 1869 followed by a degree in mining engineering from Harvard’s Hooper School. After participating in the Hayden Survey he went to work as Chief Geographer for the new U.S. Geological Survey, where he spent the rest of his career, during which “most of its methods of map-making were developed under his direction” (Darton). He was at times detached to the Department of the Interior to work on the Censuses of 1880, 1890 and 1900, in which capacity he oversaw numerous publication efforts to render census data in easily-accessible cartographic form. Among his many interests was forestry, which presumably explains his commission of Sprague to produce this atlas. Gannett was a founder of both the Association of American Geographers and National Geographic Society and was President of the latter from 1910 until his death.
In all, an early and important thematic atlas and a valuable record of an American landscape that is much changed in the intervening 140 years.
References
Phillips, Atlases, #1187. Rumsey #2332. Background on Sargent from “Sargent, Charles Sprague (1841-1927)” on JSTOR’s Global Plants web site. Background on Sprague from N. H. Darton, “Memoir of Henry Gannett”, Annals of the Association of American Geographers, vol. 7 (1917), pp. 68-70.