There are 13 US Post Offices in Lewis County serving a total of 23,647 residents equating to 1,819 residents per post office. It's estimated that approximately 37,743 packages are handled across the 13 county post offices annually. Lewis County is a county located in the U.S. state of New York. As of the 2010 census, the population was 27,087, making it the fourth-least populous county in New York. Its county seat is Lowville. The county is named after Morgan Lewis, the Governor of New York when the county was established."