About the Texas Slavery Project Maps
The Texas Slavery Project's interactive maps are delivered with the HistoryBrowser, a tool developed by the Virginia Center for Digital History at the University of Virginia. Cartographic work was done using ESRI's ArcGIS suite of tools, which allowed the Project to combine historical and modern information about the geography of Texas into a single set of historically accurate maps. The GIS materials were then exported to the HistoryBrowser, where they were combined with the MySQL database of slave and slaveholding populations in 1837-1845 Texas to produce the Project's online maps.
Creating the County Boundaries
The county boundaries for the Republic of Texas were created using Luke Gournay's historical atlas Texas Boundaries: Evolution of the State's Counties as a base, making small changes as needed based on historical information. Gournay's work details the development and changes in the county boundaries beginning in 1836, showing the annual changes in county boundaries.
These maps were modified to match the boundaries as they existed at the time of the tax assessments (which provided the data in the Texas Slavery Project's database) in the Republic of Texas. Gournay's map of 1837 Texas, for example, includes several counties created in December 1837 after the tax assessments for that year were collected.
Similarly, the offical boundaries of Bexar during 1837-1845 covered a vast area including much of modern-day West Texas. The tax assessments for Bexar from that period, however, reflected a much smaller area, mostly the general area surrounding San Antonio. Accordingly, a smaller county boundary for Bexar was added to the Gournay maps using the 1856 county boundary of Bexar around San Antonio as a guide.
According to Gournay, Rusk County was not created until 1843. Tax returns for slaveholders in Rusk County began appearing in 1842, however, reflecting the fact that slaves and slaveholders lived and farmed in the area by 1842 and tax records for these people were complied under Rusk County. Consequently, Rusk County appears in the TSP maps in 1842.