ZIP code 91784 is officially located in the state of California, primarily serving the city of Upland. It falls under the administrative jurisdiction of San Bernardino County. When planning mail delivery, logistics routing, or demographic research, 91784 operates within the Pacific Time (PT) timezone and supports the 561 area codes.
According to the latest US Census Bureau and American Community Survey (ACS) datasets, the total population residing within the 91784 ZIP Code Tabulation Area is approximately 21,561. Understanding local economics is critical for market analysis; the median household income in this postal area sits at $68,784.