Calendar changes affect genealogists

Did you know that the calendar we use is not the same calendar that your ancestors used? Have you run into dates in your research that just don’t make sense? It may be because of the change in calendars.

Calendars and the calculation of time have been influenced over the years by different cultures and beliefs. Because of this, dates are not uniform and have changed as a result of morphing political powers and cultural transformation. This affects genealogists because dates changed when calendars did.

The Julian calendar was introduced by Julius Caesar in 45 B.C.E. Before the Julian calendar was introduced, priests in the Roman Empire exploited the calendar for political ends, inserting days and even months into the calendar to keep the politicians they favored in office. Tired of the chaos that this undependable system eventually gave rise to, Julius Caesar determined to put the long-abused calendar in order. The Julian calendar is still in use in some countries today but has been replaced by the Gregorian calendar.

The Gregorian calendar was proposed by Aloysius Lilius, a physician, and sanctioned by Pope Gregory XIII to correct for errors in the Julian Calendar. It was decreed by the Pope in a papal bull on February 24, 1582. Though Pope Gregory's reform was enacted in the Catholic Church, the bull had no authority beyond the Catholic Church and the Papal States. The changes which he was proposing were changes to the civil calendar over which he had no authority. The changes required adoption by the civil authorities in each country to have legal effect. Most Catholic countries adopted the new calendar in the 1580s but it took until 1929 before the majority of the world had accepted it. This can cause confusion to a researcher because people can appear to die before they were born, or in Orthodox countries, they may have two different birth dates!

Different areas in what is now the United States changed at different times. The Eastern seaboard (which includes Massachusetts, Maine, Connecticut, New York, Rhode Island, New Hampshire, Vermont, Pennsylvania, Maryland, Delaware, Virginia, North and South Carolina and Georgia) changed in September of 1752. The Mississippi valley changed in December 1582. Texas, Florida, California, Nevada, Arizona, New Mexico changed in October 1582. Washington and Oregon adopted the new calendar in 1752. Alaska did not switch over until October 1867 when it became part of the USA.