From the record
“The International Boundary Marker, also known as the Republic of Texas Granite Marker, is a boundary marker located on the Louisiana-Texas border near the junction of Texas Farm to Market Road 31 and Louisiana Highway 765, southeast of Deadwood, Texas. The marker was created in 1840 and placed in 1841 to mark the international border between the United States and the Republic of Texas.”
Wikipedia article International Boundary Marker, CC BY-SA 4.0.
One of 3 National Register listings published here for Panola County · listed in 1977 · category: Object.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service