Since this was the lone wasp, I am wondering if she is the queen. She was fertilized last fall and has overwintered, usually in a tree (or mailbox?). She will build the nest herself and start laying eggs. When her babies hatch, they will then help feed the others. Sometime around late summer she will start laying more male eggs and they will mate with the female young wasps and these will be the queens for the following year. I gathered this information here and here.
Paper wasps are considered beneficial in that they feed on other insects and, thankfully, not rural mail carriers.
Linda's Note: In case you are wondering why you read this post yesterday and this little lady was identified as a hornet and now its a paper wasp, it is because Chip (who I usually check with before I post any identification) steered me in the proper direction. Thanks Chip!