How can I trigger an automatic push notification when a user enters any one of several different geographic locations?

To send an automatic push when a user enters one out of multiple predefined areas, you should use Geozone Clusters:

Define Individual Geozones: First, create a separate Geozone for each specific geographic location you want to target (e.g., Location A, Location B, Location C).
Create a Geozone Cluster: Group these individual Geozones together into a single Geozone Cluster. This cluster acts as a collection of all the relevant locations.
Set Up Automation: Configure an automated campaign or journey. Use the "User Enters Geozone Cluster" event as the trigger, selecting the cluster you created in the previous step.
Configure Push Message: Define the content of the push notification that should be sent automatically when a user enters any of the Geozones contained within that cluster.

This setup allows you to manage multiple physical locations under a single automated push campaign rule.