ZIP code 61104 is officially located in the state of Illinois, primarily serving the city of Rockford. It falls under the administrative jurisdiction of Winnebago County. When planning mail delivery, logistics routing, or demographic research, 61104 operates within the Central Time (CT) timezone and supports the 790 area codes.
According to the latest US Census Bureau and American Community Survey (ACS) datasets, the total population residing within the 61104 ZIP Code Tabulation Area is approximately 39,990. Understanding local economics is critical for market analysis; the median household income in this postal area sits at $108,104.