In an executive order, Obama also noted that the heads of departments and agencies may determine that "certain offices and installations of their organizations, or parts thereof, must remain open and that certain employees must remain on duty for the full scheduled workday" on Christmas Eve.
Traditionally, presidents grant employees an extra day of vacation when Christmas falls on Tuesday or Thursday. This year it is on a Friday.
Last year, when Christmas fell on a Thursday, President Bush ordered executive branch agencies to close on the next day, Friday, Dec. 26, giving most federal employees a four-day weekend over the Christmas holiday.
The last time Christmas fell on a Friday, in 1998, President Clinton gave federal workers a half day off. At that time, a White House spokesman said the half day was something of a tradition in years when Christmas falls on a Friday.
In 2002, when Christmas fell on a Wednesday, Bush gave federal workers a half day of vacation on Tuesday.