[Pittsburgh, September 24. Image via Getty]

PITTSBURGH - SEPTEMBER 24: A protestor cries from tear gas fired on marchers by riot police during an unpermitted march against the G-20 Summit on September 24, 2009 in Pittsburgh, Pennsylvania. Marchers gathered in neighborhoods several miles from Pittsburgh's downtown but were dispersed by police bearing tear gas and amplification machines. Dignitaries begin arriving for the G-20 Summit today while authorities vow to prevent expected protests from disrupting the meeting. (Photo by Chris Hondros/Getty Images)