There are 4 US Post Offices in Phelps County serving a total of 46,488 residents equating to 11,622 residents per post office. It's estimated that approximately 74,200 packages are handled across the 4 county post offices annually. Phelps County is a county located in the central portion of the U.S. state of Missouri. As of the 2010 census, the population was 45,156. The largest city and county seat is Rolla. The county was officially organized on November 13, 1857, and was named after U.S. Representative and Governor of Missouri John Smith Phelps. According to the U.S. Census Bureau, it included the mean center of U.S. population in 2000. Phelps County comprises the Rolla, MO Micropolitan Statistical Area. Much of the county is included within the Ozark Highlands American Viticultural Area (AVA). Vineyards and wineries were first established in the county by Italian immigrants in Rolla. Since the 1960s, winemakers have revived and created numerous vineyards in Missouri and won national and international tasting awards. The first Phelps County Court convened on November 25, 1857 in the John Dillon cabin. The historic courthouse was begun in mid-summer of 1860, used as a Union hospital during the American Civil War and served as the courthouse until February 1994, at which time all county offices were relocated in the new Phelps County Courthouse. The new courthouse was dedicated on May 22, 1994."