What is a good UX for a Single Select Dropdown with an All option?

Question

I saw Should multi-select dropdown/box have an "all" option? but it is different.

This is for a Web UX.

EDIT:

This is a form that generates a report. The user chooses from a list of "locations" to include in their report. The number of locations will differ for each user. Let's say there are between 5 and 25 locations.

Answer 1

Your users have a binary choice (single or all), then potentially an additional required choice.

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I'm not sure of your user's common workflow or use case, but you could consider defaulting the radio button selection to "Single Location". This would require user intervention regardless (i.e. actually select a location, or select "All Locations") so there's no risk of the user accidentally submitting with incorrect prepoulated data.