The permanent PWPs like the Police Station, Reset Center, Campsite and The Roost (cafe) don't count.
I'm not sure if the first bridge still counts if you demolish and remodeled it because some people say it does. I changed mine to Modern bridge and going by that theory, I'd have 31 PWPs built in my second town. If not, that'd be exactly 30 excluding the permanent PWPs.
I haven't counted lately, but I know I have quite near 30. My villagers never say anything about PWP's anymore, so they must be satisfied. I know I am! If I could get another fence, I would, but alas!