There are 2 US Post Offices in Buffalo County serving a total of 1,676 residents equating to 838 residents per post office. It's estimated that approximately 2,675 packages are handled across the 2 county post offices annually. Buffalo County is a county located in the U.S. state of South Dakota. As of the 2010 census, the population was 1,912. Its county seat is Gann Valley which, at 14 people, is the least populous county seat in the United States. The county was created in 1864 and organized in 1871 as part of the Dakota Territory. In 2010, the center of population of South Dakota was located in eastern Buffalo County. The Crow Creek Indian Reservation inhabited by the Crow Creek Sioux Tribe makes up the majority of Buffalo County. According to the 2013 Small Area Income and Poverty Estimates (SAIPE) of the Bureau of the Census, about 41% of county residents live in poverty, making it the fifth-poorest county in South Dakota. This is a far higher poverty rate than the national poverty rate, which is 15.8%. Median household income in 2013 was $21,572, making it the lowest-earning county in South Dakota and one of the lowest-earning counties in America. In March 2015, the unemployment rate was 8.5%; its ten-year peaks occurred in December 2006 (18.%) and December 2009 (17.2%). Many homes lack kitchens and indoor plumbing."