
Officials have covered up a noose on display near polling booths in Missouri, after local Democrats argued it could intimidate black voters.
The incident is one of a number of controversial occurrences in the final days of the US election campaign.
Meanwhile a Democratic campaign bus in Texas was encircled by supporters of President Donald Trump, a Republican.
And a rally to promote voting in North Carolina ended with attendants getting pepper-sprayed and arrested.
There are widespread fears across the country of post-election violence, whether the election is won by Mr Trump or his Democrat challenger Joe Biden.
Businesses in downtown Washington DC have been seen in recent days boarding up their premises amid concerns about looting.