Here’s a look at some interesting events that took place on this day in history:

1469: Ferdinand of Aragon marries Isabella of Castile in Valladolid, beginning a cooperative reign that would unite Spain and elevate the nation to a dominant world power (more info)

1648: Boston Shoemakers form the first US labor organization (more info)

1767: The boundary between Maryland and Pennsylvania, better known as the Mason-Dixon line, is agreed upon (more info)

1867: United States takes possession of Alaska after purchasing it from Russia for $7.2 million (more info)

1974: Soul singer Al Green is attacked in his home by an ex-girlfriend, who later shoots herself dead (more info)