There are 13 US Post Offices in Lassen County serving a total of 59,703 residents equating to 4,593 residents per post office. It's estimated that approximately 95,293 packages are handled across the 13 county post offices annually. Lassen County is a county located in the northeastern portion of the U.S. state of California. As of the 2010 census, the population was 34,895. The county seat and only incorporated city is Susanville. Lassen County comprises the Susanville, California micropolitan statistical area. A former farming, mining and lumber area, it has an economy today dependent on employment at two state and one federal prison; the former two in Susanville and the latter in Herlong. In 2007 half the adults in Susanville worked in one of the facilities."