Donald Trump declared "the work begins" as hundreds of thousands of people poured into Washington DC to welcome - or oppose - his inauguration as the 45th president of the United States.
The tycoon-turned-politician took to Twitter yet again to send an early morning message to a nation bitterly divided by his election victory.
Mr Trump has pledged to unify America as he prepares to be sworn in amid plans for widespread protests and a boycott by dozens of politicians.
Protesters gathered outside Union Station waved placards which read "unity against racist Trump" and chanted "the people united will never be defeated".
Scott Williams, from protest group J20 Resist, said: "We planned this protest before the election because no matter who won ... movements like this and Black Lives Matter are the only future."
Demonstrators clashed with police outside a pro-Trump rally in Washington on Thursday night, while one group, DisruptJ20, has said it will try to shut down or cause delays at security checkpoints at the inauguration ceremony.
Speaking at a concert at the Lincoln Memorial on the eve of his inauguration, Mr Trump told supporters: "We're going to unify our country. We're going to make American great for all our people. We're going to do things that haven't been done for our country for many, many decades. It's going to change."
After forecasters predicted rain in Washington DC on Friday, Mr Trump added: "I don't care frankly if it's going to be beautiful or if it's going to rain like crazy. It makes no difference to me. I have a feeling it's going to be beautiful."