Planet Money did a podcast on the subject: https://www.npr.org/sections/money/2018/08/01/634737852/episode-857-the-postal-illuminati https://www.npr.org/section

Planet Money did a podcast on the subject: https://www.npr.org/sections/money/2018/08/01/634737852/episode-857-the-postal-illuminati https://www.npr.org/sections/money/2018/08/01/634737852/epis... There is a fixed rate between postal offices to ship overseas, and it may make the shipping cheaper when coming from China.