As the march progressed, numerous police officers walked along the edges of the demonstration, maintaining a visible but low-profile presence in their normal blue-shirt duty uniforms.

Despite the easygoing atmosphere, the crowd at the head of the march began shouting, "(expletive) the police!" as the procession neared the Loop. As the crowd chanted insults at officers walking alongside them, some demonstrators turned to Deputy Chief Matt Tobias and said, "It's not personal" and "It's systemic, it's not you."

Tobias, one of the top commanders on the street, shrugged and bantered a bit with the marchers, asking one of them what would happen if there were no police. The young man replied, "It would be really bad."

Despite such tension, the atmosphere remained civil. As demonstrators closed in on Federal Plaza, police on horseback joined the front of the march.

While some demonstrators shouted "free the horses," one police supervisor walking backward at the head of the march was tapped on the shoulder by a demonstrator who pointed out he was about to step in a large pile left by one of the horses. The officer thanked the man.

At the plaza, some of the protesters chanted, "Hey hey, ho-ho, Rahm Emanuel's got to go."

Dori Ewing said she was there to protest the mayor's treatment of unions, primarily the teachers union. She's not a teacher but has friends in a number of unions.

"If they mess with the teachers union, what's going to stop them from messing with the rest of them," Ewing said. "Without unions there would be no middle class."

Reuters contributed from Cleveland.

dheinzmann@tribune.com

jcoen@tribune.com

rhaggerty@tribune.com