The Big Date Change of 1751

Item of the Week From the East Hampton Library Long Island Collection

This month, most of us will be struggling to remember the new year when we write down the date. If you grapple with this annually, can you imagine having to write three different years in a span of 367 days? If you think the extra day in leap year is confusing, imagine skipping 11 days, which actually happened in September 1752. People went to bed on Sept. 2 and woke up the next morning on Sept. 14.

This was part of the Gregorian calendar change, which took place following Pope Gregory’s realization that a 20-minute difference in calculating the length of a year could really add up over a few thousand years. When Pope Gregory issued an order for Catholic countries to change their calendars and catch up in 1582, Britain had recently dumped the Catholic Church in order to do its own thing in terms of church and state. Most mainland European countries made the change sooner, leading to dates written with two years, like “February 22, 1722/1723.” This was known as double dating.

In January 1750, the British government finally gave in and decided to change the empire over to the Gregorian calendar. Parliament passed An Act for Regulating the Commencement of the Year, a copy of which is seen here. The act outlined the steps required for this convoluted changeover and strove to make sense of the steps one needed to line up the two calendars.

Before the Gregorian calendar, the year legally started on March 25, so the act also switched the start of the new year to Jan. 1. In the first phase of the calendar change, the year didn’t change to 1751 on the day after Dec. 31, 1750. Instead, the next day was Jan. 1, 1750. The year finally changed to 1751 on the day after March 24, 1750. 

For the last step, the entire British Empire jumped ahead 11 days to sync with the new calendar, making the day after Sept. 2, 1752, into Sept. 14, 1752. 


Andrea Meyer is a librarian and archivist in the East Hampton Library’s Long Island Collection.