I was walking back to my car at the Muir Woods parking lot today. Earlier as I was coming in I saw an LE ranger issuing tickets to private cars parked in the prime commercial-vehicle only parking spots (most spots open to any vehicle after 4 PM). On the way back I got a look at the envelope. I don't remember exactly what it said on the top, but the address was in Philadelphia.
I was under the impression that stuff like citations for vehicle code violations would have to be processed in the county where they were issued, although I'm thinking it might be different in a federal jurisdiction. I was under the impression that someone contesting a ticket would have to do so in a Federal Court, such as the Yosemite courthouse.