Suburban growth would have been impossible without?

Answer 1

The car. Until the car was invented the city center was the main shopping and business district of an area. People built homes within walking or trolley distance of the center and very little was done away from the main district. When the car was invented it allowed people to move away from the downtown districts and as roads and freeways were built more and more people moved away from the center. This created suburban growth and as more people lived outside of the city center more services were needed. So, stores were built and eventually malls were added to the areas. This also created a need for more services and business.