I also went out to the same U S. Post Office Tuesday 2/15/2000. It was a bit colder; near 40 or 41 dry Degrees F. This time i heard the postal employees talking about my lack of shoes as i left. I took this cool photo of my soles while sitting in front of the famous Independence Hall. I had walked thru the building and none of the Federal Park Rangers said a word. They have this wonderful laid brick floor in the main hall way. You can stop into the big room where they worked out and sign the Declaration of Independence in July of 1776. They have carpeted the floors where the public stand to help keep the climate of the room just right to preserve the artifacts of that historical room. It was tremendous contrast in the feeling on my soles.
I also stopped into a coffee shop named XANDO. They did not seem to notice my barefeet, so i may have made a mistake asking the manager on duty what their policy was. He said they did not allow it, but not to worry about it. He did not require me to put on shoes either. I guess it's one of those places where enforcement is at the discretion of the manager on duty. During the warm months of the year they have out door tables and i assume they don't enforce it out doors.