Suburbs arose out of a complex set of social factors. (2) One factor was the economic and technological developments that made it possible for people to live far from where they worked. (3) Early in this century, most people were limited in where they could live by the need to find transportation to work. (4) This meant that most had to live in the cities near where the jobs were. (5) Because there were relatively few automobiles and highways, people walked or used public transportation to get to work and go shopping. (6) This encouraged the concentration of population, and central cities served as the commercial and cultural core of urban areas. (7) By the 1940s and 1950s, the increasing prosperity of many Americans, along with the automobile, made it possible for them to live farther from work and opened up suburban life to middle-class Americans. (8) In addition, government policy was also a factor contributing to suburbanization. (9) First of all, the government paid 80 percent of the cost of developing the interstate highway system. (10) With cars and high-speed highways, people can now live far from where they work and shop. (11) In sprawling cities such as Los Angeles, for example, it is common to live fifty or more miles from where you work. (12) Also, government agencies made available federally guaranteed mortgage loans for the purchase of new homes. (13) Because land outside of the cities was both inexpensive and available, this is where much of the construction took place. A2. Specifically, the major details of the passage are