What changed in the 1920's that caused cities to expand outward?

In the 1920s, several factors contributed to the outward expansion of cities, notably the rise of the automobile, which made commuting easier and encouraged suburban development. The availability of affordable housing and the construction of new roadways facilitated this movement, allowing people to live farther from their workplaces. Additionally, the growth of industries and the desire for more space and greenery led families to seek homes outside urban centers, fostering the growth of suburbs. This shift marked a significant transformation in urban planning and living patterns during the decade.