Marla just entered a contest where she had to guess how many letters a given letter carrier (postman, actually post-woman?) was going to deliver that day. In googling, I didn't find an answer to that question. So here's my guess, based on the most authoritative sources I can find.
So it's pieces of mail per carrier per day. The number of pieces of mail delivered per day by the United States Postal Service is about 509 million, according to the USPS. Now we need to know the number of letter carriers in the US. This number is about 315,950, according to the Bureau of Labor Statistics. Dividing, we get that the average letter carrier delivers about 1,611 pieces of mail per day in the United States. You're welcome.