Nightly calculated from nearby places having this postcode. Documentation .

You can search for those with an Overpass Turbo query.

How Nominatim uses postcodes.

{#if country_code === 'gb'}

Additionally supplemented by Ordnance Survey Code-Point® Open data. UK Postcode data for Nominatim

{/if} {#if country_code === 'us'}

Additionally supplemented by data derived from US Census (TIGER) data.

{/if}