Google will determine and store the location of any Wi-Fi access point whose SSID (name) does not end with "_nomap".
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Control access point inclusion in Google's Location services - Google Maps Help
https://support.google.com/maps/answer/1725632
To improve Location services and estimate the location of a device, Google uses publicly broadcast Wi-Fi information from wireless access points and GPS, cell tower, and sensor data. This data is limi