Editing 1791 (section)

=== April&ndash;June ===
* [[April 21]] &ndash; The first of forty [[boundary markers of the original District of Columbia]], delineating the borders of the new District in the United States is laid at [[Jones Point Light]] in [[Alexandria, Virginia]].
* [[April 29]]–[[May 8]] &ndash; The first American ships reach [[Japan]], [[brigantine]] ''[[Lady Washington]]'' captained by [[John Kendrick (American sea captain)|John Kendrick]] of [[Boston]], and the [[brig]] ''Grace''.<ref>{{cite web|title=First Encounters Between the U.S. and Japan - John Kendrick...|url=https://www.ny.us.emb-japan.go.jp/history/01.html?id=eng|publisher=Consulate General of Japan in New York|accessdate=2022-09-03}}</ref><ref>{{cite web|title=Logbook for Brig "Grace" (1791)|url=https://duxburyhistory.org/collection-highlights/logbook-for-brig-grace-1791/|publisher=Duxbury Rural & Historical Society|accessdate=2022-09-03}}</ref>
* [[May 3]] &ndash; The [[Sejm of the Polish–Lithuanian Commonwealth]] proclaims the [[Constitution of May 3, 1791]], the first modern codified [[constitution]] in Europe.
* [[June 20]] &ndash; [[French Revolution]]: [[Flight to Varennes]] &ndash; The French Royal Family is captured when they try to flee in disguise.
* [[June 21]] &ndash; The [[Ordnance Survey]] is founded in Great Britain for the production of maps.<ref>{{cite web|url=http://www.charlesclosesociety.org/files/HistoryOSGB.pdf|title=A short history of the Ordnance Survey of Great Britain}}</ref>