President and vice president sworn in officially on Sunday before public ceremony on Monday . Obamas and Bidens led volunteers in National Day of Service on Saturday to honor Rev . Martin Luther King . Chelsea Clinton , honorary chairwoman of the Day of Service , said at a kickoff event on Mall that Saturday was the 19th anniversary of her father former President Bill Clinton signing the bill that designated a National Day of Service to coincide with Sunday 's events included concerts , fireworks and Obama thank - you to donors . Monday 's crowds expected to be about half of those who gathered in D.C. in 2009 .
President and vice president sworn in officially on Sunday before public ceremony on Monday . Obamas and Bidens led volunteers in National Day of Service on Saturday to honor Rev . Martin Luther King . Sunday 's events included concerts , fireworks and Obama thank - you to donors . Monday 's crowds expected to be about half of those who gathered in D.C. in 2009 .