Delaware Boundary Markers
Mason-Dixon Monument Oct 11.jpg
Mason–Dixon Monument, October 2011
LocationState boundary lines between DE-MD/DE-PA, Delaware
Area0 acres (0 ha)
Built1763 (1763)
ArchitectMason, Charles; Dixon, Jeremiah
NRHP reference No.75002101[1]
Added to NRHPFebruary 18, 1975

Delaware Boundary Markers is a national historic district located on the State boundary lines between Delaware, Maryland, and Pennsylvania. The district includes 94 contributing sites along the Mason–Dixon line and includes the Transpeninsular Line, "Post Marked West" site, Mason–Dixon line, Tangent Line, The Arc, and The 12-Mile Circle.[2]

It was added to the National Register of Historic Places in 1975.[1]


  1. ^ a b "National Register Information System". National Register of Historic Places. National Park Service. July 9, 2010.
  2. ^ Edward F. Heite (October 1974). "National Register of Historic Places Inventory/Nomination: Delaware Boundary Markers". and Accompanying photo