You probably didn’t notice, but macOS High Sierra keeps an ongoing list of recurring locations. The feature is called Significant Locations, and according to Apple is used by Maps, Calendar, and Photos to “provide useful location-related information.”
This location information is locally encrypted, and not shared with Apple, but you might want to review, delete, and even disable the feature. And you can, but it’s a little buried.
First open up System Preferences, then head to Security & Privacy.
Head to the “Privacy” tab. Click the lock at bottom left, then enter your password. Make sure the “Location Services” option is selected in the left panel, then scroll the right panel down until you see “System Services.” Click the “Details” button.
Here you’ll see a list of operating system features that can use your location, including the new Significant Locations feature. You can disable the feature by unchecking, but to see the currently stored locations you’ll have to click the “Details” button. Like we said: this is somewhat buried.
Click the button and you’ll see a list of cities you’ve used your laptop in recently; expand those cities and you’ll see specific locations. For me the feature correctly identified my house in Hillsboro, Oregon, and the house in California I spent a week at for work. There’s no way to delete individual locations, but you can click the “Clear History” button to wipe everything.
Right now, it seems like macOS isn’t making a lot of use of this information, but it’s easy to imagine things like Siri recommending when to leave for work based on your routine. It’s potentially cool, but some users might want to disable it. Happily Apple gives you the choice.