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Calendar Adoption

Calendar Adoption

While Spain, Portugal, the Polish Lithuanian Commonwealth and most of Italy adopted the "Gregorian" Calendar in October 1582, not all countries and locations adopted the refined calendar at the same time. For example, the American Colonies did not adopt the "Gregorian" Calendar until September 1752 (170 years later). Therefore, October 1582 would appear as it had before, but September 1752 drops out 11 days (1 more than in 1582 due to accumulating more error). Turkey did not adopt the new calendar until 1926. Some examples of when countries adopted:

Country Year Changed Change Days Skipped Days In Month
Spain, Portugal, the Polish-Lithuanian Commonwealth, and most of Italy 1582 October 15, 1582 follows October 4, 1582 10 October had 21 days
U.S.A. (Arizona, California, Florida, Nevada, New Mexico, Texas, with Spain) 1582 October 15, 1582 follows October 4, 1582 10 October had 21 days
France,* Loraine 1582 December 20, 1582 follows December 9, 1582 10 December had 21 days
U.S.A. (Mississippi Valley with France) 1582 December 20, 1582 follows December 9, 1582 10 December had 21 days
Dutch provinces of Brabant, Zeeland and the Staten-Generaal 1582 December 25,*24 1582 follows December 13, 1582 10 December had 21 days
Austria 1583 ? 10 ?
Provinces forming the Southern Netherlands (modern Belgium) 1583 January 1,*31 1583 follows December 20, 1582 10 December had 21 days
Denmark, Flanders 1583 January 5, 1583 follows December 25, 1582 10 December had 25 days, January 1583 had 27 days
Holland 1583 January 12,*13 1583 follows January 2, 1583 10 January had 21 days
Catholic Switzerland 1584 ? 10 ?
Hungary 1587 ? 10 ?
Scotland 1600 ? 10 ?
Protestant Netherlands, Denmark (included Norway and some portions of Germany (Protestant)) 1700 March 1, 1700 follows February 18, 1700 11 February had 18 days (and a leap year)
Remaining provinces of the Dutch Republic 1700/1 • July ?, 1700 follows ? ?, 1700 (Gelderland)
• December ?, 1700 follows ? ?, 1700 (Utrecht and Overijssel)
• January ?, 1701 follows ? ?, 170? (Friesland and Groningen)
11 July had 20 days, December had 20 days, January 1701 had 20 days
Sweden Intentional: 1700-1740 Intentional: Supposedly dropped February 29, 1700. Gradual shift dropping leap years for 40 years (til 1740) except it did not happen for 1704 and 1708 leap years, and an attempt to revert back to the Julian calendar failed with the attempt to add February 30, 1712 (See 1753 below). Does this mean February still had 29 days in leap years for 1704, 1708, but had 28 days for 1712, 1716,1720,1724,1728,1732,1736,1740, or no changes at all? It is likely there was no change because Sweden did drop 11 days in 1753, which got them back on track (see below). 0 (11 intended) No change ever occurred???
Great Britain, American Colonies (see below) 1752 September 14, 1752 follows September 2, 1752 11 September had 19 days
U.S.A. (Eastern seaboard, Washington, Oregon as British colony) 1752 September 14, 1752 follows September 2, 1752 11 September had 19 days
Sweden, Finland 1753 Thursday, March 1 follows 17 February 11 February had 17 days
Remainder of Switzerland 1812 ? 11 ?
Alaska 1867 October 18 follows October 6 11* October had 20 days
Korea 1896 ? 12 ?
Japan 1873 ? 12 ?
China, Albania 1912 ? 13 ?
Russia 1918 Thursday, 14 February 1918 follows Wednesday, 31 January 1918 13 February had 15 days
Yugoslavia, Romania (Non Eastern Orthodox Church) 1919 ? 13 ?
Greece 1923 Thursday, 1 March 1923, follows Wednesday, 15 February 1923 13 February had 15 days
Eastern Orthodox church in Romania, Yugoslavia, and Greece 1924 ? 13 ?
Turkey 1926 January 1st, 1927 follows December 18th, 1926 13* December had 18 days (1-18).

Months with unusual number of days

  • October 1582 had 21 days (Catholic countries, including Spanish controlled territories in what is now the U.S. states of Arizona, California, Florida, Nevada, New Mexico, and Texas)
  • December 1582 had 21 days (France, Loraine, some Dutch provinces, Southern Netherlands, U.S.A. Mississippi Valey)
  • December 1582 had 25 days (Denmark, Flanders)
  • January 1583 had 27 days (Denmark, Flanders)
  • January 1583 had 21 days (Holland)
  • February 1700 had 18 days (Denmark that then included Norway and parts of Germany)
  • July 1700 had 20 days (Gelderland)
  • December 1700 had 20 days (Utrecht and Overijssel)
  • January 1701 had 20 days (Friesland and Groningen)
  • February 1712 had 30 days (Sweden)
  • September 1752 had 19 (Great Briton, American Colonies, Eastern Seaboard, Oregon, Washington)
  • February 1753 had 17 days (Sweden and Finland)
  • October 1867 had 20 days (Alaska)
  • February 1918 had 15 days (Russia)
  • February 1923 had 15 days (Greece)
  • December 1926 had 18 days (Turkey)

Months with unusual number of days by year

Month Days Year Country
October 21 1582 Catholic Countries
December 21 1582 France, Loraine, some Dutch provinces, Southern Netherlands
December 25 1582 Denmark, Flanders
January 27 1583 Denmark, Flanders
January 21 1583 Holland
February 18 1700 Denmark that include Norway and parts of Germany
July 20 1700 Gelderland
December 20 1700 Utrecht and Overijssel
January 20 1701 Friesland and Groningen
February 30 1712 Sweden
September 19 1752 Great Briton, American Colonies, Eastern Seaboard, Oregon, Washington, Great Briton, American Colonies, Eastern Seaboard, Oregon, Washington
February 17 1753 Sweden and Finland
October 20 1867 Alaska
February 15 1918 Russia
February 15 1923 Greece

Months with unusual number of days by Month

Month Days Year Country
January 27 1583 Denmark, Flanders
January 21 1583 Holland
January 20 1701 Friesland and Groningen
February 30 1712 Sweden
February 18 1700 Denmark that included Norway and parts of Germany
February 17 1753 Sweden and Finland
February 15 1918 Russia
February 15 1923 Greece
July 20 1700 Gelderland
September 19 1752 Great Briton, American Colonies, Eastern Seaboard, Oregon, Washington, Great Briton, American Colonies, Eastern Seaboard, Oregon, Washington
October 21 1582 Catholic Countries
October 20 1867 Alaska
December 25 1582 Denmark, Flanders
December 21 1582 France, Loraine, some Dutch provinces, Southern Netherlands
December 20 1700 Utrecht and Overijssel

Therefore, March, April, May, June, August, and November are the only months that have never had their number of days changed. Note that August has had 31 days since it was named August (changed from Sextils to August by Augustus Caesar, who also added the 31st day).

Other Calendars

If you wish, I have found a simple full year calendar from PaulSadowski.com.

Try this online full year calendar from TimeAndDate.com. You can generate a calendar for any year using their online form.

If you wish to see a month at a time, I have also found a very accurate generic calendar* that uses the 1582 calendar switch adopted by Pope Gregory. It correctly shows the year 1582 when Pope Gregory declared that October 4th would be followed by October 15th for Italy, Spain, and Portugal ("Catholic" countries). Keep in mind this is not correct for the American Colonies (part of the British Empire, and mostly Protestant), as they did not change until September 1752. Parts of the "New World" were under control of France and Spain in 1582, and had already made the change by then.*