There are 3 US Post Offices in Guadalupe County serving a total of 4,785 residents equating to 1,595 residents per post office. It's estimated that approximately 7,637 packages are handled across the 3 county post offices annually. Guadalupe County is a county located in the U.S. state of New Mexico. As of the 2010 census, the population was 4,687, making it the fifth-least populous county in New Mexico. Its county seat is Santa Rosa."