This series contains an inventory of Boundary Markers (Milestones) along the Mason-Dixon Line. Each container holds multiple binders that document a range of markers. The binders are organized by milestone maker sequentially from the northeast corner of Maryland and moves westward by Mason and Dixon's mile number. An example of a binder's title is 0-7 (1-8). The "0-7" refers to markers 0 through 7. The numbers in parentheses are by monument as assigned by the 1900-03 Resurvey of the Maryland-Pennsylvania boundary and are listed for cross-reference information. Each marker is documented on a field sheet. The sheet includes information such as location, directions to the site, description/measurements, condition of the marker and the surrounding property. Each marker sheet may include photographs, slides, negatives, and/or maps. The condition section of the sheet includes the condition reports of prior inspections. A portion of this series includes material that documents milestones between West Virginia and Pennsylvania as well.