My friends moved out of the city to a commuter area outside LA when they were starting their family. The tiny new houses were sweet, and everyone was from somewhere else but at the same phase of life. New elementary school, the families came together and formed a vibrant happy working class community. Kids playing outside, BBQs. Racially mixed.
Then Los Angeles started moving poor people in from the city for free.
Suddenly the neighborhood was full of crack cocaine and crime. There were shootings. It became a horrible place to live and the housing values were so low my friends were paying a fortune for a worthless house. They packed up and moved away leaving the keys in the door. Their credit was back to normal 5 years after that but the area today is known as a den of urban filth and decay.