The modern "Gregorian" or "Western" calendar, which most countries use for official business, was first adopted in the year 1582 by Italy, Spain, Portugal and the countries under Polish-Lithuanian influence. To get the calendar in sync with the solar cycle, ten days were skipped in October. Therefore Thursday, October 4 was immediately followed by Friday, October 15. Most other countries did not make the solar-sync at the time, and calendars remained inconsistent among many modern nations until 1923, when Greece finally made the switch. Countries under the influence of the British Empire, including what would be the US and Canada, made the switch in 1752, making Thursday, September 14 immediately follow Wednesday, September 2. To see the North American calendar for 1752, surf here: https://www.timeanddate.com/calendar/?year=1752&country=1 ObTrivia: DR's b'day did not occur in 1752 in North America.