There were 32 arrests in Washington on Wednesday night, after demonstrators tried to block entrances to the Internal Revenue Service, while 30 others were arrested outside a congressional office building, police said.
Protesters had hoped to shut down the IRS, the US tax collection agency, to highlight the cost of the war. Police cleared the building's entrances within an hour.
In San Francisco, long a centre of anti-Iraq war sentiment, police arrested 143 who protested through the day along Market Street, in the central business district. Sergeant Steve Maninna said charges included trespassing, resisting arrest and obstructing traffic.
Four women were detained for hanging a large banner off the city's famous Golden Gate Bridge and then released, said bridge spokeswoman Mary Currie.
On Washington's National Mall, about 100 protesters carried signs that read: "The Endlessness justifies the Meaninglessness" and waved upside-down US flags, a traditional sign of distress.
"Bush and Cheney, leaders failed, Bush and Cheney belong in jail," they chanted, referring to President George Bush and Vice-President Dick Cheney.
One hour after the IRS stand-off, several dozen protesters waved signs that read: "Stop Paying to Kill" and "How Much Longer?" as a ragtag brass band played. IRS employees were easily able to enter the building.
"We wanted to put our bodies between the money and what that money goes to fund - the war, the occupation, the bombs," said Frida Berrigan, an organiser with the War Resisters' League.
The war has cost the US $US500 billion ($A548.6 billion) since the invasion to topple Saddam Hussein began in March 2003. Tens of thousands of Iraqis have been killed and millions more displaced, with almost 4000 US soldiers killed.
Later, scores of noisy protesters blocked a busy intersection in Washington's business district. They picketed in front of the offices of The Washington Post and threw red paint on the building that houses the Examiner newspaper and Bechtel National Inc, which has handled major reconstruction projects in Iraq.
In New York, about 30 members of the "Granny Peace Brigade" gathered in Times Square, knitting in hand, to demand troops be brought home now.
© 2008 Reuters