Every year, the Emerald Society, an association of Irish Chicago police officers, flies in policemen from New York City for Chicago's two big St. Patrick's Day Parades.
A postman explains how it is that he can be so much a part of the scenery that people commit crimes in front of him, on quiet daytime streets, as if he's not there. This American Life producer Alex Blumberg spent a day with postman on Chicago's west side, to find out what he sees...and who sees him...and who doesn't see him, even though he's right there.