Mark Zuckerberg, the founder of Facebook, likes making and keeping New Year resolutions. In recent years he has learnt Mandarin, read 25 books, run one mile every day, and created a robot-butler to organise his home. But this year his New Year resolution is more high-minded than usual. ‘My personal challenge for 2017,’ he writes, ‘is to have visited and met people in every state in the US by the end of the year.