When did people start using the Gregorian calendar?

Search: gregorian calendar

Why: The New Year is nigh.

Answer: 1582! Before that, everyone used the Julian calendar, which had been in place since 45 B.C. Though pretty accurate, it erred from the real solar calendar by 11½ minutes a year, which added up over time. By the 16th century, the Julian calender was behind the solar one by 10 days.

In 1582, Pope Gregory XIII ordered the advancement of the calendar by 10 days. He also and introduced a new corrective device to curb further error: century years such as 1700 or 1800 would no longer be counted as leap years, unless they were (like 1600 or 2000) divisible by 400. Now, the Gregorian calendar year differs from the solar year by only 26 seconds, which adds up to only one day's difference every 3,323 years.

Source: infoplease

The More You Know: Despite the accuracy of Pope Gregory's correction, many Protestant countries ignored the papal bull (lol). Germany and the Netherlands adopt the Gregorian calendar in 1698, Russia after the revolution of 1918, and Greece in 1923.

And there was the British Calendar Act of 1751:

In England, the year 1751 was a short year of 282 days, running from 25 March to 31 December. 1752 began on 1 January.

To align the calendar in use in England to that in use on the continent, the changes introduced in 1582 by the Gregorian calendar were adopted with effect in 1752. To this end, the calendar was advanced by 11 days: 2 September 1752 was followed by 14 September 1752.

Many Orthodox churches still follow the Julian calendar, which now lags 13 days behind the Gregorian. And the Hebrew calendar (it is now the year 5770) started with the creation of Adam.