Since I did address database software for public libraries for a couple of
decades....  Addresses are complicated.

In North American (USA & Canada) there are approximately 80,000
localities, counties, states and federal addressing authorities (mostly
local building and planning departments). These are the official (legal)
addressing authorities.  Tax and real estate records usual the legal
property definition.



Because its a PITA to deal with 80,000 different authorities...

The USPS (and Canada Post)) maintains a national directory of addresses
valid for mailing purposes.  Not every address. The addresses they
deliver based on local jurisdiction address information, but modified for
postal needs.

The telephone company (formerly Ma Bell, then ILECs, now PSAPs and states)
maintain the Master Street Address Guide (MSAG) for E911 purposes. Again
based on local jurisdication address information, but modified for
telco/cellular/PSAP needs.

The US Census maintains TIGER and Master Address File (MAF) for planning
enumeration operations every 10 years. Geocodes domiciles (i.e. where
people live, not work) for census workers, not necessarily postal or
telephone addressses.

Several commercial (i.e. expensive) databases for various purposes, such
as driving, mapping, advertising, etc; all use one of the government
address databases as their base. Enhance the base information with
satellites, airplane and street view mapping.


When a record is wrong, figuring out the source is a bit of an art.

Mail/Shipping/Ecommerce => start with USPS database

Telco/wireless/E911 => start with MSAG database

Politics/Gerrymandering => start with Census database

Tax, real estate, other => start with local building/planning department


On Thu, 30 May 2024, Mike Hammett wrote:
> This is the Internet, after all, so I will be corrected if I'm wrong.
> 911 is based on MSAG (Master Street Address Guide), not USPS. However, many
> operators are likely using the USPS system to sanitize the inputs.