There are 5 US Post Offices in Willacy County serving a total of 22,060 residents equating to 4,412 residents per post office. It's estimated that approximately 35,210 packages are handled across the 5 county post offices annually. Willacy County is a county located in the U.S. state of Texas. As of the 2010 census, its population was 22,134. Its county seat is Raymondville. The county was created in 1911 and organized the next year. Willacy County comprises the Raymondville, TX Micropolitan Statistical Area, which is included in the Brownsville\u2013Harlingen\u2013Raymondville, TX Combined Statistical Area."