New York (CNN) -- A mix of protesters gathered again Friday in cities across the country, decrying a loosely defined list of financial problems and mixing in places with others marking the 10-year anniversary of the U.S.-led invasion of Afghanistan.
Demonstrators in New York and Washington appeared to congregate over both the Afghan conflict, arguably America's longest war, and in protest against the widening disparities between rich and poor and corporate greed, among other grievances.
New York Police Commissioner Ray Kelly said an investigation is under way after protesters claimed officers used excessive force when corralling demonstrators earlier this week.
He also noted that demonstrations had cost tax payers $1.9 million in overtime costs for the city's law enforcement.
CNN affiliate stations also broadcast images of crowds that gathered in Austin, Texas, as well as Minneapolis, Minnesota; Seattle, Washington and Atlanta, Georgia.
The activity came a day after President Barack Obama discussed the growing movement, saying demonstrators "are giving voice to a more broad-based frustration about how our financial system works."
Speaking at a White House news conference, Obama also defended the country's financial sector, which has taken the brunt of protesters' criticism, focusing on Wall Street and its regulators' purported role in expanding economic disparities.
"We have to have a strong, effective financial sector in order for us to grow," the president said.
Still, Obama discussed a need to pursue action aimed at improving government oversight and blamed Republican lawmakers for obstructing financial reforms.
Friday marked the 21st day of the grass-roots Wall Street protests.
Demonstrations have erupted in more than a dozen cities throughout the week, ranging from thousands who marched in lower Manhattan Wednesday after receiving support from local unions, to the dozens of college students who staged walkouts at various college campuses.
The movement started in New York and some of the protests there have been marred by scuffles with police.
New York authorities set up at least one vehicle checkpoint as police appeared in larger numbers throughout the financial district Thursday and established a perimeter around Zuccotti Park, which is considered a rallying point for the largely leaderless movement in that city.
"We hope that our message continues to resonate with everyone who has felt disenfranchised by the current state of our country," said Tyler Combelic, a spokesman for the Occupy Wall Street group.
He said they plan to "continue the protest until the message reaches every house in the United States."
The specifics of that message remains largely unclear.
CNN's Susan Candiotti, Carey Bodenheimer, Ross Levitt and Jason Kessler contributed to this report.