FERGUSON, Mo. — As residents swept broken glass from the sidewalks Wednesday and painted hopeful messages on boarded-up storefronts, public officials cautiously said that tighter security measures and hundreds of additional National Guard troops had helped stabilize this St. Louis suburb after a night of arsons, looting, and violence.
But under daylong snow showers, anger and frustration over a grand jury's decision on Monday not to indict a white police officer in the August killing of Michael Brown, an unarmed black teenager, remained palpable across the region.
West Florissant Avenue, a commercial strip now being treated as a crime scene after an arson spree, was still barricaded by police Wednesday. National Guard troops in camouflage uniforms, who were largely limited to protecting government buildings two nights earlier, fanned out across the city, taking up positions along street corners and at intersections.
Throughout demonstrations Tuesday night, the Guard responded to disturbances, turning back demonstrators from a drugstore that had been surrounded by the police and helping officers make arrests outside the Police Department.
Although windows at City Hall were shattered and a police car was flipped and burned, law enforcement officials said the more assertive response had helped curb the chaos that prevailed on Monday.
Governor Jay Nixon, whom local officials have criticized for not mobilizing enough security forces during the worst violence, said Wednesday that "the ramped up presence and action of the Missouri National Guard has been helpful."
He did not announce additional security measures, but said he would continue to monitor conditions here. About 1,200 Guard troops have been in and around the St. Louis region, up from 700 early this week.
Across the country, largely peaceful protests resumed over the grand jury's decision, with hundreds of people once again pouring into streets. In St. Louis, about 200 protesters staged a mock trial of the police officer, Darren Wilson, and at one point marched on the steps of City Hall, chanting loudly.
As the demonstrators gathered just outside the entrance, dozens of officers, many in riot gear, moved in and ordered the protesters to disperse. Some reluctantly complied, but others challenged why they were not allowed to be there.
In Southern California, demonstrators chanting "Black lives matter" closed the 101 freeway for a time Wednesday, echoing tactics that had brought traffic to a standstill in cities across the country a day earlier.
In New York City's Harlem neighborhood, members of Brown's family and their supporters appeared at a prayer event organized by the Rev. Al Sharpton. Sharpton and Benjamin Crump, a lawyer for the Brown family, again criticized how St. Louis County prosecutors had handled the investigation into Brown's death and said the grand jury process seemed tilted in Wilson's favor.
"They try to vilify our children but put the shooter on a pedestal," Mr. Crump said. "We scratch our heads and say, 'Why does this happen over and over again?' "
Although unrest in Ferguson had diminished dramatically from Monday night, when the town endured the worst violence since Brown's killing, residents and officials were concerned about flare-ups over the Thanksgiving holiday, which could bring more people into the region.
The outcry over the grand jury's decision was also reshaping life in subtler ways. The Thanksgiving Day parade in St. Louis was postponed because of the unrest, and some people were urging a boycott of the traditional Black Friday shopping as a protest against inequalities in the justice system.
For many, Brown's killing laid bare myriad issues of racial inequality.
On Wednesday, federal officials said they would investigate the burning of a church on West Florissant Avenue where Brown's father was a congregant. Carlton Lee, the pastor of the Flood Christian Church, which was gutted on Monday night, said he believed his church had been targeted by arsonists because of his public calls for Wilson's arrest.