The border wars between New York and New Jersey have seen fierce fighting over the years, from actual shots fired in the 18th century to trash-talking and legal wrangling over the ownership of Ellis Island almost into the 21st.

Now, a librarian in the neutral territory of Massachusetts has uncovered a long-lost document from those tangled disputes: a hand-drawn map that may be the earliest surviving one showing New Jersey’s northern border where it is today.

The map, which is owned by Harvard University, was created by the celebrated colonial surveyor Bernard Ratzer in 1769, at the request of a royal commission charged with settling the long-burning northern border dispute once and for all.

It was found by John Overholt, a curator of rare books and manuscripts at the university’s Houghton Library, rolled up in a container and stacked with some uncataloged material.