Tens of thousands of law enforcement officers and miles of barriers were in place in Washington on Friday, as officials braced for hundreds of thousands of people planning to celebrate or protest Donald Trump's inauguration as president of the United States.

U.S. civil rights activists vowed on Saturday to defend hard-fought gains in voting rights and criminal justice during the presidency of Donald Trump, kicking off a week of protests ahead of the Republican's inauguration.

The Washington Monument closed on Sunday when the elevator in the marble obelisk failed for the second time this weekend, the latest in a string of problems for the system, a spokesman said.

Undeterred by heightened concerns about safety at protests after a lone gunman killed five police officers in Dallas Thursday night, organizers went ahead with marches in the biggest metropolis, New York City, and Washington D.C., the nation's capital, among other cities.

US district court Judge ruled no ban on concealed firearms and ordered police have no right to ask for a good reason when people want to carry a gun in public.