Four people were stabbed and taken to hospital with "serious injuries" and 23 people were arrested.
The day had started with a festive atmosphere as thousands of protesters with red berets filled the streets of Washington in support of the President, and were not deterred by the rejection of the US Supreme Court of what might be his last chance to cancel the results.
Similar events occurred in Olympia, Atlanta and St. Paul, Minnesota, as well as in smaller cities in Nebraska, Alabama and elsewhere.
Although election results have been confirmed by state election officials, many of them Republicans, and judges in several major states, pro-Trump protesters have found their own explanations for the election result.
All states have now certified the election results, with Biden awarding 306 votes in the Electoral College to 232 for Trump, but the protesters insisted that there was widespread fraud in the elections.