population_code_for_zip represents the resident population of the ZIP Code in which the business is located.
Population Code is based on information from the 2010 SF1 Census. Whenever possible, the total population of a ZIP Code is mapped directly to Data Axle's business database. If no exact match is available, then total population will be derived from county-level population figures. By subtracting known ZIP Code populations from the known county populations, we can arrive at a "remaining" county population, which will then be distributed to any previously unassigned ZIP Codes associated with that county. Any remaining ZIP Codes that were unable to be associated with an SF1 county population will be assigned as a missing value.