It was by far the most vigorous protest since both parties began meeting to formally nominate their presidential candidates this year. Republicans gathered last week in Tampa, where just two protesters were arrested by the end of the three-day affair.
Tuesday's demonstration started when a half-dozen Vietnam-era veterans calling for better medical care and other issues were joined in an unauthorized march by dozens of members of the Occupy movement, which was protesting the incarceration of a soldier accused of leaking documents to WikiLeaks.
About 50 protesters disrupted traffic by sitting down in the middle of the intersection. They were quickly surrounded by heavily armed officers in riot gear. A police major using a loudspeaker urged the protesters to enter a nearby fenced-in area designated by the city for permitted convention demonstrations.
"All of America used to be a free-speech zone," said John Murdock, 37, a protester from New York who came to Charlotte after protesting last week at the Republican convention in Tampa.
Gesturing toward the many officers, he added: "This stuff is right out of George Orwell."
The impasse ended after two protesters spoke with the Charlotte police chief and said they were told they could continue to walk as a group on public sidewalks as long as there was no violence. They then continued past the city's convention center, which is hosting some convention-related activities for delegates. The facility several blocks from the arena is also where most media are staged.
The demonstrators' stated goal had been to talk with convention delegates, and the two groups mingled outside the convention center. Some were seen shouting at each other through a line of police officers who were separating them with mountain bikes.
At one point, a group of delegates shouted "Four more years!" The marchers, some of whom carried anti-Obama signs, responded: "No more years!"
As the march continued, protesters turned onto the main thoroughfare of North Tryon Street toward the corporate headquarters of Bank of America, situated in the city's tallest skyscraper. Still, the path police were allowing them to take kept them at least two blocks away from the convention hall, a sports arena heavily fortified with rings of steel fencing and police barricades.