If this trivia section was presented each week as a question I would ask what holiday is only celebrated in Missouri. And the answer...Truman Day, a commemorative holiday to celebrate the birth of Harry S. Truman, the 33rd President of the United States.
It is celebrated May 8 in Missouri as a state holiday, and nationally by the United States Democratic Party. Since Truman was the only president to come from Missouri, this day is special for this state.
However, after the financial crisis of 2008-2010, there were unsuccessful moves by the state government to abolish the holiday which is a paid day for Missouri state employees.