Most of those taking part in the demonstration said they were not doing so to support one Iranian candidate or another. Instead, they said they were there to show support for the Iranian people's rights to protest the results of an election they question.
One man at the protest led chants translated, "The people united will never be divided" and "No more violence, no more blood." The protest in Chicago, like others across the United States, were being streamed live to Iranian chat rooms with the hope that the citizens would know they have the backing of people the world over.
"Everyone is upset, and everyone wants to be counted as a human being. This suffering has gone on for far too long," said protestor Parissa Behnia.
"All I can say is this is the most activity and the most violence and the most energy and the most movement that we've seen in Iran since the revolution in 1979," said Nassim Nazemi, also a protestor.
"Iran deserves democracy, and dictatorship has to stop," protestor Amir Normandi said.
The rally, and others like it around the country, came together via posts in chat rooms and on social networking sites like Facebook and Twitter, and that is exactly how participants hoped to get the word out.
It's also been an interesting phenomenon in Iran. While the Internet has been cracked down on in recent days there, it is the social networking sites that are helping get the word out about protests.
Those with family still in Iran say they have increasing concern over the government crackdowns, especially now that leaders in Iran have said protests should end.