Mercury was one of the first places in the solar system to be colonized, due to it's vast mineral wealth. However, no one wanted to actually live there. Instead it had a temporary population of workers, who would operate mobile mining platforms, constantly "chasing the night" as the planet slowly spun. Tiny cities were gradually established at the poles, (which had deposits of ice in permanently shadowed craters,) that could house families, and send rescue teams whenever a mining platform broke down. This status quo changed about a century later, when the Second Space War broke out. The asteroid belt became a warzone, and suddenly Mercury was a safe haven. The war eventually ended, but Mercury's cities continued to expand. Today they are among the most populated in the Solar System.