In this article, we'll cover Route Codes and how to activate them.
Route codes are an optional additional field that you can enable for all of your user's Billing and Shipping Addresses. This feature is not turned on by default and must be enabled in your Admin Dashboard.
Enabling route codes is straightforward. You'd go to the admin side of your website, and then scroll down to Config and click on User and Form Settings>Address Options
The Enable Route Codes checkbox is on the address options page.
Check the box and hit "Save". The route codes will now show up on the Shipping and Billing addresses for all of your customers.