Kairos Quarterly, a new journal published by the Orthodox Hermitage of the Holy Cross in West Virginia, writes about the interesting phenomenon of Old Calendar Protestants:
As a Russian Orthodox monastery which observes the Julian, or “old”, calendar, we were surprised to learn about Appalachian “Old Christmas”, which is a most solemn and reverent time for families living in the mountains. The initial change-over from the Julian calendar to the Gregorian calendar by the British Empire and the American colonies in 1752 caused a difference of eleven days. Thus, the date of “new” Christmas on December 25th was eleven days ahead of “old” Christmas, which fell (at that time) on January 5th. Some Protestants refused to honor the new calendar because it was decreed by the Pope, so their celebration of Christmas remained on the Julian calendar – which now falls on January 7. In the Appalachian Mountains, the celebration of Old Christmas remained until about World War I. Though they might also observe ‘new’ Christmas on December 25th, the festivities were very different. December 25th was marked with revelry and parties and visiting, but January 6th was primarily a reverent family observance.
Orthodox Christians in the United States still observe the Julian calendar, either in its traditional or revised form (the old and new calendars, respectively—note that the “new calendar” does not refer to the Gregorian calendar followed by most western Christians), depending on their jurisdiction.
Hat tip to William August Wilson, IV.