Creation of freeway system to create accessibility into the city ripped apart neighborhoods, dislocating many people. This caused a massive upheaval of people from the city into the suburbs.
Movement into the suburbs stimulated the need for multiple cars in order to get the simple necessities of daily life such as groceries. Shopping malls centralized the consumer needs into one location, accessed by a car.
The city began to decompose due to the lack of people living there. Car business still boomed due to commuters who still had jobs in the city.