The first and most important reason for growth of European cities was shortage of jobs in the farming industry. This was the start of the large migration to the city. The second most important reason was the improvements in health in sanitation. This idea of good hygiene was attractive to people, and also let people live longer and reproduce more, increasing the population. The 3rd most important reason was the effective sewage system and cleaner water. This ties in with the second reason, adding to the good hygiene the cities were gaining
