There is an old vaudeville joke that goes like this. What is worse than a oneweek vacation in Philadelphia? The answera twoweek vacation in Philadelphia. The reason: Philadelphia rolls up its sidewalks after dark.

It's unfair, of course, to label Philadelphia in this way. In the years preceding and immediately following World War II, most American cities were like Philadelphia. Almost everything in them, from retail outlets to radio stations, was packed away for the night. The idea of stores and restaurants and food markets staying open through the night was relatively unheard of. (1)

Until recent times, the night has been viewed as somewhat hostile. Why? The absence of light. Walking in the dark is a fearful experience. At night thieves and murderers ply their trade. At night the drug d…