36 U.S.C. § 141
Thomas Jefferson’s birthday
The President shall issue each year a proclamation—
(1)
calling on officials of the United States Government to display the flag of the United States on all Government buildings on April 13; and
(2)
inviting the people of the United States to observe April 13 in schools and churches, or other suitable places, with appropriate ceremonies in commemoration of Thomas Jefferson’s birthday.
( Pub. L. 105–225 , Aug. 12, 1998 , 112 Stat. 1262 .)