ZIP code 91931 is officially located in the state of California, primarily serving the city of Guatay. It falls under the administrative jurisdiction of San Diego County. When planning mail delivery, logistics routing, or demographic research, 91931 operates within the Pacific Time (PT) timezone and supports the 342 area codes.
According to the latest US Census Bureau and American Community Survey (ACS) datasets, the total population residing within the 91931 ZIP Code Tabulation Area is approximately 17,842. Understanding local economics is critical for market analysis; the median household income in this postal area sits at $67,931.