There are 9 US Post Offices in Henry County serving a total of 20,787 residents equating to 2,310 residents per post office. It's estimated that approximately 33,178 packages are handled across the 9 county post offices annually. Henry County is a county located in the U.S. state of Iowa. As of the 2010 census, the population was 20,145. The county seat is Mount Pleasant. The county was named for General Henry Dodge, governor of Wisconsin Territory."