So, one of the most recognized social facts among criminologists is that violent crime and crimes against property are more commonly found in certain areas of a city and less commonly found in others. This is no surprise, but the interesting thing is that as people who live in the crime ridden sections move out, the crime, by and large, stays. That is, it doesn't move with them. This was something criminologists discovered way back in the 1920s. Today, the reasoning and argument are much more complicated than was the case back in the day. For instance, it's now also widely recognized that some of the high rates of crime in particularly urban areas are also due to the high rates of policy surveillance, so that some of the difference in crime rate is due to the simple fact that some areas of the city aren't crawling with police. Despite this issue of visibility and enforcement on crime rate numbers, the fact remains. As people move out of crime prone areas, the crime tends not to move with them. The reason people believe this is an important social fact is because it make us ask about crime as a function of an individual, where it's due to one's psychological makeup or genetics or a function of conditions/environment. That is, an area as criminogenic, where crime is a somewhat normal reaction to abnormal conditions.