WASHINGTON BORO, Pa. (WHTM) — On Route 441 in Manor Township, Lancaster County, is a marker erected by the Safe Harbor Water Power Corporation. It commemorates the 40th parallel, an imaginary line that caused real trouble for two English colonies.

The 40th parallel or, if you will, 40 degrees north latitude, was set as the northern boundary of the Maryland Colony in a charter granted in 1632. No problem! Until 1681, when William Penn received a charter for Pennsylvania. His colony was supposed to start where Maryland left off, but the map British authorities used while drawing up the charter was hopelessly inaccurate.

For one thing, it misplaced New Castle, Delaware.

A circle with a radius of 12 miles was to be drawn around New Castle until it met the 40th parallel, but New Castle is so far south there is no way that circle could reach that line of latitude. So the Pennsylvania border as set out in the charter was well south of the 40th parallel- and so was the new town of Philadephia. In fact, the Maryland and Pennsylvania border claims overlapped by about 28 miles.

The proprietors, Maryland Calverts and Pennsylvania Penns, dug in their heels and refused to yield an inch of ground. The arguments went on for over 80 years, sometimes getting a bit heated – as in shots fired. (A lot of this conflict played out along the lower Susquehanna, in Lancaster and York Counties.)

Eventually, calmer heads prevailed, with a little nudging from the British government. Both sides gave a little, and a compromise border was reached – 39 degrees, 43 minutes north latitude. After a meticulous survey by Misters Charles Mason and Jeremiah Dixon, the border was set in stone, literally, with a marker stone set every mile.

And speaking of markers, that 40th Parallel marker sits exactly on the 40th parallel, intersecting with 76 degrees 28.447 minutes west longitude.