"There is no opting out. No control over your personal information," Republican Senator Josh Hawley said in a tweet.
Facebook said that clues for figuring out a user's location include being tagged in a photo at a specific place or a check-in at a location such as at a restaurant during a dinner with friends.
People may share an address for purchases at a shopping section at Facebook, or simply include it in their profile information. Along with location information shared in posts by users, devices connecting to the internet are given IP addresses and a user's whereabouts can then be noted. Those addresses include locations, albeit a bit imprecise when it comes to mobile devices linking through telecom services that might only note a town or city. Facebook said knowing a user's general location helps it and other internet firms protect accounts by detecting when suspicious login behavior occurs, such as by someone in South America when a user lives in Europe.
IP addresses also help companies such as Facebook battle misinformation by showing the general origin of potentially nefarious activity, such as a stream of politically oriented posts which might be aimed at a particular country.