Mesoamerican Long Count calendar Mesoamerican Long Count calendar The Mesoamerican Long Count calendar is a non-repeating, vigesimal (base-20) and base-18 calendar used by several pre-Columbian Mesoamerican cultures, most notably the Maya. For this reason, it is often known as the Maya (or Mayan) Long Count calendar. Using a modified vigesimal tally, the Long Count calendar identifies a day by counting the number of days passed since a mythical creation date that corresponds to August 11, 3114 BCE in the Proleptic Gregorian calendar. The Long Count calendar was widely used on monuments. The two most widely used calendars in pre-Columbian Mesoamerica, were the 260-day Tzolk'in
Adoption of the Gregorian calendar when a 13th Julian leap day was skipped in 1900, so the tax year in the United Kingdom still begins on 6 April. The European colonies of the Americas adopted the change when their mother countries did. In 1752, the British colonies (which as stated above adopted the New Style calendar in that year) extended as far west as the Appalachian Mountains. New France and New Spain had adopted the new calendar in 1582. In Alaska, the change took place after the United States purchased Alaska from Russia. Friday, 6 October 1867 was followed by Friday, 18 October. Instead of