In August of 1859, surveyors marked the 100th Meridian at the Red River - the line that marks the eastern boundary of the Texas panhandle and the western boundary of today's Oklahoma.
This boundary between New Spain and the United States was established by the Adams-Onis Treaty of 1819 but not properly surveyed until several decades later, after Marcy's journeys through the Comancheria (the Comanche territory). Surveyors Brown and Jones created a simple but beautiful map that illustrates two witness trees south of the Initial Monument and acknowledges the phonetically-spelled Comanche name for the Main Red River, Keche-ah-que-ho-no. This map is relatively long, so one feature I wasn't able to capture with this portion is the "Prairie Dog Town" that the surveyors illustrated at the 11th mile north. So, make sure to see it at the Texas General Land Office when clicking on this link: https://s3.glo.texas.gov/glo/history/archives/map-store/index.cfm#item/3091
