Although taking the oath of office on a Bible has been customary since George Washington was sworn in, U.S. presidents are not required to do so. Lyndon Johnson used a Catholic prayer book when he assumed office. John Quincy Adams used a book of laws. Theodore Roosevelt used nothing.

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The Surprisingly Disorderly History of the U.S. Presidential Succession Order

In 1981 U.S. Pres. Ronald Reagan was shot during an assassination attempt. While he was incapacitated in the hospital, Secretary of State Alexander Haig famously declared, “I am in control here.” He also told reporters, “Constitutionally, gentlemen, you have the president, the vice president, and