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Calendar Adjustment Day

History · Fun · September 2

A look at how calendars drift and get corrected, from leap days to the switch that once made the American colonies skip days.

Calendar Adjustment Day falls on Thursday, September 2, 2027. That is 310 days away.

Calendars are approximations. The Earth takes a little longer than 365 days to circle the Sun, and that leftover fraction of a day has to go somewhere. Every calendar people have used is, in part, a plan for handling it.

The Julian calendar handled it with a leap day every four years. That came close, but it ran slightly long, and over a very long time the calendar slid out of step with the seasons. The Gregorian calendar fixed this by skipping the leap day in most century years. Only those divisible by 400 keep it.

Switching from one system to the other meant dropping days outright. When Britain and its American colonies made the change, the calendar jumped forward eleven days. People went to bed on one date and woke up on a much later one. Rents, wages and birthdays all had to be sorted out afterward, which sounds like a bookkeeper's long week.

The adjustment still shows up in odd places. Old records sometimes list two dates for the same event, marked Old Style and New Style. George Washington's birthday is one familiar case, since he was born before the switch and his birth date shifted with it.

The day itself is mostly marked with curiosity. People look up how leap years work, compare a few historical dates in both systems, or simply check that the calendar on the wall still agrees with the one on their phone. It always does, thanks to that rule about the years divisible by 400.

Ways to celebrate

• Look up the leap year rule and test it on a few years.
• Find an old document listing both Old Style and New Style dates.
• Ask a library about colonial records from the calendar change.
• Share the eleven skipped days story with someone who has not heard it.

Dates

All national days on September 2

Also on September 2

• V-J Day
• National Blueberry Popsicle Day

Categories: History daysFun days