ZIP code 51101 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, 51101 operates within the Central Time (CT) timezone and supports the 364 area codes.
According to the latest US Census Bureau and American Community Survey (ACS) datasets, the total population residing within the 51101 ZIP Code Tabulation Area is approximately 18,564. Understanding local economics is critical for market analysis; the median household income in this postal area sits at $57,101.