ZIP code 51111 is officially located in the state of Iowa, primarily serving the city of Sioux city. It falls under the administrative jurisdiction of Woodbury County. When planning mail delivery, logistics routing, or demographic research, 51111 operates within the Central Time (CT) timezone and supports the 446 area codes.
According to the latest US Census Bureau and American Community Survey (ACS) datasets, the total population residing within the 51111 ZIP Code Tabulation Area is approximately 43,146. Understanding local economics is critical for market analysis; the median household income in this postal area sits at $127,111.