How do they know? Did they do a system audit?https://twitter.com/nagarockshard/status/856131196060749824 …
You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more
well, the data has to be collected somehow.
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.