The West Ridge neighborhood (also called West Rogers Park) has the unusual distinction of being the center of two types of Jewish communties at different times. Back in the 50s and 60s this was a heavily conservative/reform Jewish neighborhood. Now it's the center of an orthodox Jewish community. But there are a few remnants from the old neighborhood that have remained and seem to function just as they did. This kosher deli is one of them. On the opposite corner is Levinson's bakery, which falls into the same category.
It's hard to see with this scan, but there's a number 48 in the oval sign on top. I believe it refers to USDA Establishment 48, which is Best's Kosher inspection designation. Oddly, Best's Kosher is now owned by Sara Lee.