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
Seriously if @twitter really wants to maximize engagements, they should have a manual mode because the people who care the most would probably do it for free.
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.