Herbert Hoover Second inauguration took place on April 30 , 1789 , and not in the city named for him . As allowed by the the 20th Amendment , only two presidents chose to `` affirm '' rather than swear their oaths . Obama will be sworn-in twice ; once on January 20 in private and again on January 20 in public . Inaugurations were predominantly on March 4 until 1937 . The oath for other federal officials , including the vice president , is not in the Constitution . Since , January 20 is the date .
Herbert Hoover Second inauguration took place on April 30 , 1789 , and not in the city named for him . As allowed by the the 20th Amendment , only two presidents chose to `` affirm '' rather than swear their oaths . Obama will be sworn-in twice ; once on January 20 in private and again on January 20 in public . Inaugurations were predominantly on March 4 until 1937 . Since , January 20 is the date .