WASHINGTON • Some wore shirts with an image of President Donald Trump as the Monopoly mascot hauling a bag of money.
Others taunted Mr Trump with signs saying they would show him their taxes, if he showed them his.
And in front of a few thousand people on the lawn of the US Capitol there was an oversized inflatable chicken with hair resembling Mr Trump's, suggesting the US leader is "too chicken" to release his tax returns to the public.
Throughout the country, in Seattle, the District of Columbia, Florida and New York City, protesters called on Mr Trump to release his personal tax returns as part of a nationwide Tax March.
The protest fell on the country's traditionally recognised deadline to file taxes, April 15.
In all, dozens of protests occurred throughout the country. The main march unfolded in the nation's capital, where protesters gathered for a rally in front of the Capitol and then marched.
In South Florida, activists marched to Mr Trump's Mar-a-Lago resort, where the president stayed over the weekend. Activists, comedians and a state senator spoke at a large march of thousands in New York City.
Many of the protests featured an inflatable chicken, a mascot of sorts for the march.
Presidents are not required to release their tax returns, but have done so voluntarily from the 1970s.
Activists and others say it is the only way to be fully open about any potential conflicts of interest.
In the nation's capital, the crowd was mostly filled with locals and Spring Break tourists, some of whom purposely planned their trips to coincide with the march.
Ms C.J. Ingram, a Washington resident in her 50s who works in a funeral home, attended the march, her first protest during Mr Trump's term. "I'm really mad because he made Barack Obama produce his birth certificate, and he's not even producing his tax returns."
Mr Trump has refused to release his tax returns, stating that he has been under audit.
Asked on Thursday about the Tax March, the White House referred to comments earlier from press secretary Sean Spicer, who repeated that Mr Trump is under a tax office audit, but that the president has been transparent with his finances.
The non-profit Electronic Privacy Information Centre filed a suit on Saturday over Mr Trump's tax returns, citing a provision in Internal Revenue Service regulations that allows their release.
Senator Ron Wyden, a Democrat, said: "If you don't release your taxes, we have no way of knowing if you are putting America first, or Donald Trump first."