National Guard troops have been sent en masse to Washington DC, to deter any repeat of last week's deadly riots.
The FBI has warned of possible armed marches by pro-Trump supporters at all 50 state capitols.
Meanwhile, the Biden team has set out plans to reverse key Trump policies.
In the hours after Mr Biden sets foot in the White House, he will embark on a blitz of executive actions designed to signal a clean break from his predecessor's administration, according to a memo seen by US media.
Among the actions:
- He will return the US to the Paris climate agreement - a global pact on cutting carbon emissions
- He will repeal the controversial travel ban on a list of mostly Muslim-majority countries
- He will make wearing masks mandatory on federal property and when travelling interstate
Although Mr Biden, like President Trump, will be able to use executive orders as a means of bypassing Congress on some issues, his $1.9tn (£1.4tn) stimulus plan announced earlier this week will need to be approved by lawmakers, as will a bill on immigration reform.
Much of Washington DC will be locked down ahead of Wednesday's inauguration, with National Guard troops deploying in their thousands.