Zip codes

Following a previous entry on postcodes, we have been asked how US zip codes can be used for mortality modelling.  Most people in the USA understand the five-digit zip code, for example 20500 in the address for the White House:

The White House
1600 Pennsylvania Avenue NW
Washington, DC 20500

However, a five-digit zip code typically covers thousands of people and is therefore of severely limited use for geodemographic profiling for mortality. What is needed is the nine-digit zip code, also known as "zip plus four".  This is shown below with the same address in standard format for the US Postal Service:

The White House
1600 Pennsylvania Avenue NW
Washington, DC 20500-0003

A nine-digit zip code covers a much smaller number of households on average, very much akin to the UK postcode.  Thus, it is suitable for geodemographic profiling for mortality in exactly the same way as outlined in a recent article on insurance pricing.  You don't even need to worry that your address data doesn't always contain the full nine-digit zip code: the USPS offers a service to clean up your address database.