Historical Maps and Charts (Diving Deeper audio podcast, 12.16.10)
This map, created with data from the 1860 Census, shows the distribution of the slave population of the Southern States of the United States. Download (pdf, 2.5 MB)
Use your mouse to explore the map.
It isn't often that a map can visually display a moral issue facing a divided nation. Nearly 150 years ago, the U.S. Coast Survey – NOAA's predecessor organization – achieved that landmark representation. The map, showing the distribution of the slave population in the Southern states, is included in NOAA's new special collection of maps and charts that were produced during the Civil War.
One of the collection's most important maps is the “Map showing the distribution of the slave population of the southern states and the United States.” According to both contemporary sources and historians, President Abraham Lincoln used the map to connect military forays to his policy of emancipation.
“The map was among the first to use shading to represent the human population,” explains Capt. Albert Theberge (Ret., NOAA Corps), the chief of reference for the NOAA Central Library. “It is a prime example of how Coast Survey science aided the Union cause during the Civil War.
Created in September 1861, the map graphically displays the density of the slave population in the Southern states, based on statistics from the 8th Census, which was supervised by Joseph Camp Griffith Kennedy. Kennedy wanted to include slaves by name in the U.S. Census Report, but Congress refused. Alexander D. Bache, the U.S. Coast Survey Superintendent, allowed his staff to undertake such a map. It was created under Edwin Hergesheimer, a cartographer with U.S. Coast Survey's drawing division.
The development of this map was revolutionary for several reasons. In addition to initiating a trend of statistical cartography, its thematic display of “moral statistics” affected political change.
Northern audiences were able to see that the first states to secede were those with the most slaves. Cartographers used shading to represent the human population with the darkest areas of the maps showing the highest density slave populations. The order of secession corresponds closely to the shade densities of the map. Even more to the point, a table in the map corner shows the number of slaves in each state, and the proportion of slaves to the total population. The order of the list, from highest density to lowest, again corresponds closely to the order of secession.
According to artist Francis Bicknell Carpenter, who painted First Reading of the Emancipation Proclamation of President Lincoln in 1864, President Lincoln frequently consulted this map in considering the relationship between emancipation and military strategy. Carpenter observed that Lincoln would look at the map and send his armies to free blacks in some of the highest density areas in order to destabilize Southern order.
The NOAA connection to the map had been lost over the decades. John Cloud, Ph.D., a historian who was recovering significant Coast Survey cartographic products in NOAA’s Climate Database Modernization Program, recently discovered the connection with Edwin Hergesheimer and U.S. Coast Survey. Historian Susan Schulten made important historical contributions in connecting the map to Francis Bicknell Carpenter's painting and, in extension, to President Lincoln's strategy.
This year the nation observes the 150th anniversary of the Civil War. To help people today envision the landscapes and coastal parameters that were important to military strategies, NOAA's Office of Coast Survey has unveiled “Charting a More Perfect Union,” a special collection that includes many of the maps, charts, and sketches produced during the war by U.S. Coast Survey, NOAA's predecessor organization. This project is supported by the NOAA Preserve America Initiative, part of Preserve America, a federal initiative to preserve, protect, and promote our nation's rich heritage.