There are 22 US Post Offices in Hidalgo County serving a total of 567,805 residents equating to 25,809 residents per post office. It's estimated that approximately 906,280 packages are handled across the 22 county post offices annually. Hidalgo County is a county in the U.S. state of Texas. As of the 2010 census, the population was 774,769, making it the eighth-most populous county in Texas. The county seat is Edinburg, while the largest city is McAllen. The county is named for Miguel Hidalgo y Costilla, the priest who raised the call for Mexico's independence from Spain. Hidalgo County is also designated by the U.S. Census Bureau as the McAllen-Edinburg-Mission Metropolitan Statistical Area. It is located in the Rio Grande Valley of South Texas and is one of the fastest-growing counties in the United States."