GIS ANALYSIS OF HISTORICAL LAND RECORDS IN SOUTHERN LOUSIANA DOCUMENTS TRIBAL MIGRATION IN RESPONSE TO COASTAL LAND LOSS

Coastal Louisiana has the highest wetland loss rates in North America, with multiple causes including delta subsidence, effects of human infrastructure, oil and gas extraction activities, sea level rise, and increasing storm impacts. Native American tribes including the Grand Caillou/Dulac band of Biloxi Chitimacha Choctaw (GCDBCC), are concentrated in the southernmost parts of Louisiana, where land loss-rates are double the regional average.

The GCDBCC is preparing to petition the Bureau of Indian Affairs (BIA) for federal acknowledgment. A key BIA criterion is documentation that "a substantial portion of the group inhabits a specific area or lives in a community viewed as American Indian". GCDBCC members are spread across several small towns, several miles from lands granted to 19th C ancestors (via the 1830 treaty of Dancing Rabbit Creek), and might appear to the BIA to have lost community identity. GIS analysis of satellite imagery, historical maps, and land records provides a means to examine this history, and to investigate the hypothesis that progressive land loss drove tribal ancestors to migrate inland.

Using a genealogical database constructed by tribal elders, we researched the Bureau of Land Management database for 19th C land patents and contemporaneous survey plats showing the sections granted to GCDBCC ancestors. We converted the township/range/section locations to lat/long, and overlaid them on the 1894 USGS topographic map. In combination with the original survey plats, this shows that the GDBCC were granted lands that, while marshy in places, were distant from bodies of open water. Viewing the sections on recent orthoimagery show the extent of the change: many of the land grants are now largely or wholly open water. Tribal ancestors living on those sections would have had no option but to move away as their lands became inundated. As this was a gradual process over many decades, and as they were migrating inland into lands already occupied by mostly non-Native settlers, they had little ability to consolidate in a centralized location. However, most GCDBCC members did remain within the general region, and community structures were retained. This geoscience-based analysis will strengthen the GCDBCC petition for federal recognition.