January 20 is the date nowadays-- it used to be March 4.
Yes, when he is sworn into office he swears to uphold the Constitution.
When the President of the United States is sworn into office, he swears to preserve, protect, and defend the Constitution by taking the following oath of office : "I do solemnly swear (or affirm) that I will faithfully execute the office of President of the United States, and will to the best of my ability, preserve, protect, and defend the Constitution of the United States."
He promises to protect the US Constitution when he is sworn into office.
The Constitution of the United States of America
When a President-elect is sworn into the office of President, he rests his left hand on a closed Bible and raises his right hand. The actual Oath of Office is specified in Article II, Section 1 of the U.S. Constitution.
Lyndon B. Johnson was the only president sworn into office on an airplane.
The President is customarily sworn into office on the steps of the US Capitol building.
A national disaster does not change when the president-elect gets sworn in to office. However, it might change the location of where he is sworn in to office.
The assistant president will be sworn into office.
When a president gets sworn in and is in office. Inauguration is where they get the elected president in office.
The U.S. Constitution says that the president must take the presidential oath and be sworn in; usually, it is the Chief Justice of the Supreme Court who administers the oath. If a president is re-elected, he still has to take the oath of office a second time.
Lyndon Johnson was sworn in office on Air Force One, but I do not know of any presidents sworn in out of the U.S.