Joe Biden has become the 46th president of the United States, vowing a "new day" for the United States after four years of tumult under Donald Trump who in an extraordinary final act snubbed the inauguration. Two weeks to the day after Trump supporters violently rampaged at the US Capitol to overturn the election results, Biden took the oath on the same very steps alongside Kamala Harris, who was sworn in moments earlier as the first woman vice president.