What was Hillary Clinton doing in Katy, Texas?

During the last presidential election in the United States, Twitter drew a lot of attention. This is because many leading persons and organizations, such as U.S. president Donald J. Trump, showed a strong affection to this medium. In this work we neglect the political contents and opinions shared on Twitter and focus on the question: Can we determine and track the physical location of presidential candidates based on posts in the Twittersphere?