I have heard there is public access to power for slow chargers (so called "level one" charging) in Washington DC but we did not look them up on our trip. However I have seen them at the Lehigh Valley mall in Allentown PA and I hear the Saucon Valley mall and King of Prussia mall also has them. The security people have the electric Gem cars for patrolling, and a few spots are reserved next to their parking spots with 20 amp 120 volt GFI outlets by each one.
The photo was taken on Christmas Eve at Lehigh Valley mall, so it is not too surprising that someone parked in the spots reserved for charging electric cars. I will contact security at the mall to make sure a charging spot is available before driving the Mini E there and charging. These spots are just to the left of the Apple computer store, which is to the right of the photo frame.
It would be fun to get two or three Mini Es to go together and all charge at once.