Enhanced security for the inauguration of President-elect Joe Biden has been implemented ahead of schedule in the US capital following last week's violent siege at the Congress building.
The special security operations in Washington D.C. began on Wednesday, January 13.
They were initially scheduled to start on January 19, one day before the inauguration.
The change came after President Donald Trump's supporters stormed the Capitol on January 6.
Roads in wide areas around the Capitol and the White House have been closed to ordinary vehicles using concrete blocks and other barriers.
Building owners in the downtown area are rushing to board up their windows to guard against possible violence.
A senior Washington D.C. police official said more than 20,000 National Guard troops are expected to be deployed by Inauguration Day.
Hundreds of thousands of people usually travel to the capital from across the country to see the transfer of power. But Washington D.C. Mayor Muriel Bowser has urged people not to visit this year.
The unusual plea comes amid the continuing spread of the coronavirus and information on planned protests by people unhappy with the presidential election results.