The following article was written by my friend, Bill Dollarhide:

If you have evidence that a man had died ten months before a certain child was born, it would seem to exclude that man as the potential father of that child. But, if the calendar dates changed during the man’s life, it would be necessary to be very precise in determining the exact date of death — and he may qualify as the potential father after all. Therefore, an understanding of the change from the Julian Calendar to the Gregorian Calendar is important to genealogists.

If you had ancestors living under British rule in 1752 you need to be aware of the calendar change that took place that year. The dates you may find on documents around 1752 and later may be different than what you might expect — in fact, you may discover that a date was off by several months.

By an act of Parliament, the British Government adopted the Gregorian Calendar effective September 1752, and the change was implemented in all of the British colonies in North America and elsewhere. The United Kingdom of Great Britain was one of the later European countries to adopt the calendar change, which had been in place in parts of Europe for 170 years. The last two European countries to adopt the Gregorian Calendar were Russia in 1918 and Greece in 1923.

In 1582, Pope Gregory XIII decreed that the new calendar would be followed thereafter, and the change took place in all of the Catholic countries of Europe. The Protestant countries of Europe did not go along with Pope Gregory’s decree in 1582. The lowland states of Rhineland-Pfalz (now Germany), Belgium (then part of Holland), and the northern German states, for example, were made up of a majority of Protestant Palatines, Calvinists, or Lutherans. These groups did not adopt the Gregorian Calendar until 1700.

1582 Changes — Julian to Gregorian Calendar
There were three (3) significant calendar changes that took place in 1582 as a result of Pope Gregory XIII’s decree:

1. Drop 10 days from October 1582, to realign the Vernal Equinox with March 21st. The Julian Calendar, first adopted by Julius Caesar for the Roman Empire in 45 BC, had an annual error factor of .00636 days. From 45 BC to 1582 AD, the correct day of the Vernal Equinox using the Julian Calendar fell behind by a full ten days. Since the equinox was tied to the celebration of Easter, the Roman Catholic Church found the error undesirable.

2. Reduce the number of possible leap years. In the Julian Calendar, a leap year occurred every four years without exception. By reducing the number of leap years, the Gregorian Calendar was able to
more closely align the Vernal Equinox over centuries. The change was to make leap years for years ending in “00,” but only if the number could be divided evenly by 400. The year 2000 was a leap year (2000/400=5), while the year 1900 was not (1900/400=4.75). The reduction of leap years in the new Gregorian Calendar was all that was needed to correct the annual error factor in the Julian Calendar.
There was no change to the number of months or the number of days per month.

3. Change the first day of the year from March 25th to January 1st. This was the most dramatic change from the Julian to Gregorian Calendar, and the change that impacted genealogical dating the most. Traditionally, the new year was determined by the beginning of the four seasons, and through several centuries, the first day of Spring in the Julian Calendar was on or about March 25th.

The British Adopt the New Calendar
By the time the British finally adopted the new calendar in 1752, the correction needed to bring the Vernal Equinox back in alignment was 11 days. Britain’s Parliament chose to drop 11 days from the month of September 1752. They also declared that the first day of 1753 would be January 1st, making the English year of 1752 its shortest in history, only 280 days long. The British calendar for September 1752 appeared as follows:

George Washington’s Birthday
Today, we use the Gregorian Calendar to determine George Washington’s birthday, which took place in Westmoreland County, Virginia on 22 Feb 1732. But at the time of his birth the Julian Calendar was in effect, and the first day of the year was March 25th, not January 1st, so he was born 22 Feb 1731. His mother, Mary Ball Washington, lived her entire life believing her son was born on 22 Feb 1731. (She lived to see her son’s inauguration as President of the United States in April 1789, but died later that year).

OS, NS & Double Dating
Right after the calendar change took place in British territory, people began writing dates between January 1st and March 25th different ways, reflecting the Old Style (OS) and the New Style (NS). Genealogists may find evidence of these different styles in old records from September 1752 forward. For example, a Philadelphia lawyer could have indicated a date three (3) different ways in letters or documents written after September 1752. 1) He could have written, “February 22, 1753/4” (double dating); or 2), he could have written, “February 22, 1753” OS”; or 3), he could have written, “February 22, 1754 NS” All three styles appeared in various documents for a few years after the calendar change, but the most common use was for double dating, i.e., “1753/4,” indicating the situation of a date between January 1st and March 25th. Double-dating has become the standard style used in genealogy dating.

Any pre-1752 date between January 1st and March 24th, inclusive, should be expressed as a double date. The authors of the documents did not do it for you in most cases. There may have been some anticipation of the calendar change in the British North America before 1752, but in most cases, finding a date written as 22 February 1731/2 is rare. What was written was the Julian date of 22 February 1731.

Check the Julian Dates!
For genealogists researching in British North American records before 1752, any date found on a document and dated January 1st through March 24th is one year off. Let’s say you find a will for your great-great-great-grandfather, dated 12 March 1734. But by being a good genealogist, you find another will, or codicil, which changes the first will. Your ancestor left two documents, one which gave everything to his five sons. But the second document was dated 27 March 1735, and you think you have learned that your ancestor died after the second document was signed, or about a year after the first will. The fact is, the documents were signed only 15 days apart. The 12 March 1734 document was signed before the first of the new year, which occurred on March 25th. So, March 27th was in 1735, but only 15 days later than March 12, 1734.

In the Julian Calendar, March 24, 1734 was followed by March 25, 1735. March was also identified as the First Month. Depending on the time and place, a day/month/year date in the Julian Calendar was expressed in various ways, including:
● 3 March 1734
● March 3, 1734
● 1st mo. – 3rd day – 1734
● 3rd day – 1st mo. – 1734.

It is even possible to find such obscure Julian dates written as, 7ber 1734 or 8ber 1734 (for September and October). The Latin names for some months relate to their position in the Julian Calendar not the Gregorian Calendar. Thus October, which is a word based on the Latin number eight (octo) makes sense in the old Julian Calendar, but not in the current one, where October is the 10th month.

Exceptions in North America
Genealogist should be aware that certain groups in early America may have adopted the Gregorian Calendar before 1752, and even in British controlled territory. Thus, when a Reformed, Palatine, or Lutheran Church record in a German settlement in America is used for genealogical research, the date needs to be confirmed — were those Germans using the Gregorian Calendar or Julian Calendar? For example, the Protestant Palatine Germans had adopted the Gregorian Calendar in 1700, well before their migration to America.

In addition, the Dutch settlers along the Hudson River in New York and northern New Jersey were already using the Gregorian Calendar when they first came to America in the 1620s. After 1660, when the English took over the Dutch colonies, the Dutch people were allowed to stay and keep their way of life. Civil and church recorders of the Dutch towns continued the use of the Gregorian Calendar, even though the British governed their settlements and had not adopted the Gregorian Calendar yet. Since most of Holland had been using the new Calendar since 1583, it had become their standard for calendar dating long before they came to America.

Quaker Dates
The English Quakers who migrated to the Delaware Valley from about 1675 to 1725, left good indications of the Julian Calendar in their meeting records. In keeping with the Quaker’s desire to divest themselves of any practice of the Church of England, they did not like to use the names of the months (of which some were named after pagan gods by the Romans). So the Quakers standardized their own way of expressing a month, as the 1st month, 2nd month, 3rd month, and so on.

In early written Quaker Meeting Records, a date was commonly shown in the order of year, month, and day, e.g., 1732, 3rd mo, 24th day. After the change to the Gregorian Calendar, Quaker meeting records were more often shown in the order of day, month, and year, e.g., 25th day, 2nd mo. 1830.

Any Quaker date will include a reference to a month by its numbered position. If the date was before September 1752, Genealogists must count the months in the Julian Calendar, not the Gregorian, e.g., 1746, 3rd mo, 28th day, would translate to 28 May 1746 in the Julian Calendar. After September 1752, the Quakers, like other Americans, began writing their dates based on the Gregorian Calendar, but adding double dates for the year, e.g., 22nd day, 3rd month, 1755/6, which would be the same as 22 March 1756.

In some cases, questions about whether a Quaker date is Julian or Gregorian needs to be confirmed by looking at many dates recorded in the same record book. For example, if a genealogist finds a Quaker date expressed as the 7th month, 31st day, you would know that it refers to July, the 7th month in the Gregorian Calendar, which indeed has 31 days; while an indication of the 7th month in the Julian Calendar would represent the month of September, a month with 30 days.

The following is an example of original minutes from an 1830 New Garden Friends Meeting, Columbiana County, Ohio, now located at the Swarthmore College Historical Library, Swarthmore, PA:

What about Alaska?

In 1867, financial struggles led Russia to sell Russian America (Alaska) to the United States. The treaty was approved by Congress on 9 April 1867, and the United States flag was raised on 18 October 1867 (now called Alaska Day, a legal state holiday).

While the United States and most of Europe recognized the Gregorian Calendar, Russia had still not made the change in 1867. On the day Alaska became part of the U.S., the change from the Julian Calendar to the Gregorian Calendar caused Alaska residents to have Friday, October 6, 1867 followed by Friday, October 18, 1867. They also had their shortest year. In 1867, Alaska’s year began on March 25th and ended on December 31st. In 1867, the correction needed to make the change was 13 days, but Alaska managed to do it in 12 days (by moving the International Date Line beyond the Aleutian Islands).

For Additional Reading, see:

The Researcher’s Guide to American Genealogy, by Val Greenwood

Our Quaker Ancestors; by Ellen and David Berry


A Diary of the Dutch Reformed Church of West New Hempstead [New York]; by B. Martha Slatery Erickson, Church Historian