Visualizing Emancipation maps the end of slavery by juxtaposing three kinds of information: the legality of slavery according to the U.S. government, the marches of United States army regiments, and documentary evidence of slavery's end. Each kind of evidence required particular methods for collection and interpretation.

Legality of Slavery

The legality of slavery polygons use as their base the 1860 county boundary files made publicly available by the National Historical GIS project at the University of Minnesota. We encoded each county or territory as a space in which slavery was recognized as legal, a space in which the rights of some slaveholders were significantly compromised, or a space in which slavery was forbidden by U.S. law.

The legality of slavery was contested in much of the United States before and during the Civil War. Our map reflects the both certainty with which laws were crafted, the inconsistency with which they were interpreted by the courts, and the unevenness with which these laws were put into practice. We have interpreted the Dred Scott decision as indicating that slavery was legal throughout the territories until June 1862, when a congressional act outlawed human bondage in U.S.-organized lands.

During the Civil War Congress acted at key moments to constrain the property rights of those supporting the Confederacy. Beginning with the Confiscation Act of 1861, any slaveholder who forced those he held in bondage "to work or be employed" in support of the Confederate military effort lost the right to own them. Congress increasingly tightened these restrictions on slavery, passing An Act Prohibiting the Return of Slaves in March 1862 and a second Confiscation Act in July 1862, freeing slaves of Confederate officials and anyone else supporting the Confederacy. These laws radically changed the rights of slaveholders supporting the Confederacy. Beginning in August 1861 we change the map of the legality of slavery to reflect the fact that wherever slavery existed legally in the U.S., it was significantly impaired by these laws.

The Emancipation Proclamation, on January 1, 1863, ended the right to hold slaves in places still held by the Confederacy. This announcement did little, in practical terms, that the Second Confiscation Act had not already done. Yet the proclamation took an entirely novel geographic perspective on the institution of slavery. Whereas earlier acts of Congress declared slaves free based on the actions of individual slaveholders, the Emancipation Proclamation declared ended slavery in entire districts based upon the war powers of the executive. Accordingly, we have designated the states "and portions thereof" included in the Emancipation Proclamation among those places where the federal government did not recognize slavery beginning in January 1863.

This proclamation excluded much of the American South. It particularly excluded any state that did not secede, leaving slavery untouched in Missouri, Kentucky, Maryland, West Virginia and Delaware. Slavery ended in many of these places by state law in 1864 and 1865, though slavery became illegal in Kentucky and Delaware only with the passage of the Thirteenth Amendment in late 1865. Indian nations living present-day Oklahoma signed treaties with the U.S. abolishing slavery the following year.

Union Army Regiments

Visualizing Emancipation for the first time plots the locations of regiments in the United States army. These locations should be regarded as approximations subject to a number of caveats.

Our information on the location of U.S. regiments comes from the careful cataloging of Frederick H. Dyer, a former drummer boy in the United States Army who went on to compile the Compendium of the War of the Rebellion (1908). The Compendium supplies a nearly complete list of Union regiments during the Civil War along with detailed descriptions of those units' movements over the course of the war. The Perseus Digital Library at Tufts University digitized this text, creating approximately 3500 files, one for each regiment, encoded according to the standards established by the Text Encoding Iniitative (TEI). Scholars at Perseus used algorithms to recognize the places and dates mentioned in Dyer's text.

Scholars at the Digital Scholarship Lab transformed these files into a format that mapping applications, such as Google Earth, can read. We paired the places and dates that Perseus identified in the Compendium, then went about checking for errors.

We are aware that errors, unfortunately, remain in this dataset. These arise from a few different sources. Frederick Dyer's Compendium is quite reliable, yet even more detailed and thoroughly researched sources exist for tracking U.S. Civil War military units, particularly the Supplement to the Official Records of the War of the Rebellion. Some errors were introduced into Dyer's text through digitization, and more errors appeared during the process of identifying placenames; some historical places are not listed in even the best modern gazeteers, while other places remained ambiguous to the computational models because they are shared by multiple locations. For more information on the digitization and data extraction process, see ***. The Digital Scholarship Lab introduced further errors in computationally pairing dates and locations. While we have caught hundreds of errors, we know that many others still remain to be corrected. We are currently looking for ways to correct remaining errors in the armies dataset.

Emancipation Events

The end of slavery in the United States was a complex process that occurred simultaneously in courtrooms and plantations, on battlefields and city streets. It involved a wide variety of human interactions, many of which we represent in this map as emancipation events. We have identified ten distinct but interrelated kinds of events, which are described in more detail here:

  • Non-uniformed African Americans helping U.S. troops
  • the abuse of African Americans
  • the conscription of enslaved men and women by Confederates
  • the conscription of African Americans by the Union for labor or armed service
  • African Americans running away as fugitives
  • Orders or regulations
  • African Americans captured by U.S. military forces
  • African Americans captured or re-enslaved by Confederates
  • African American involvement in irregular fighting
  • Protecting slave property from Union troops

These event types together capture most of the events we gathered in Visualizing Emancipation. Because these types of events are interrelated, many events are encoded with multiple types.

Undergraduate researchers at the University of Richmond recorded and coded events from a number of different sources. They searched through letters, diaries, and newspapers-particularly newspapers gathered in the Valley of the Shadow project and in the Richmond Daily Dispatch. They spent by far the most time on a full canvas of the Official Records of the War of the Rebellion. In most cases, we depended on the Making of America project at Cornell University for access to these texts, though in some cases we supplemented this version with the version digitized and managed by e-history at Ohio State University.

Students searched through this corpus for words commonly used during the Civil War to refer to African American men and women in the South: contraband, negro, black, colored, slave. If the document detailed the changing practice of slavery or its dissolution, students recorded it along with a number of pieces of information about that event, particularly its date, location, and an event type.

We were not always certain where an event occurred. Some events we were sure occurred on a certain city block; we had only the vaguest sense of where others happened. Because of this uncertainty, students recorded a precision level for each event. We represent this level of uncertainty as a halo around the events: if the map displays events at a zoom level that implies greater certainty than is warranted, the event is displayed with a halo that grows larger with our uncertainty about that event.

Undergraduate students also recorded the number of African Americans affected by events. Some events describe the actions of only one or two enslaved men or women; others describe the activities of thousands. More often, the sources give only the vaguest suggestion of the numbers of men and women involved: there were "several," "many," "masses." Because these descriptions are so unreliable, we do not currently represent on the map the number of men or women involved in an event. Each documented event is represented with a dot of the same size and color.

As of February 2012, student researchers have gathered 3400 emancipation events.

Scott Nesbit