There are 4 US Post Offices in Harding County serving a total of 666 residents equating to 167 residents per post office. It's estimated that approximately 1,063 packages are handled across the 4 county post offices annually. Harding County is a county located in the U.S. state of New Mexico. As of the 2010 census, the population was 695, making it the least populous county in the state, and the 14th-smallest county by population in the United States. Its county seat is the Village of Mosquero. The county is named for United States President Warren G. Harding, and was created (from parts of Union and Mora Counties) on the day of his inauguration as President on March 4, 1921. The only incorporated cities in Harding County are Roy and Mosquero."