The way people in the US travel to and from work has changed a lot in the last fifty years.  Before the Second World War, most people lived in the town or the city where they worked.  Almost everyone either walked to work or used a good inexpensive transportation system  Many of  these systems were electrified and ran on tracks, so they used very little energy.       After 1945, the US government built many new roads and highways. People moved farther and farther form the cities where they worked because they could drive their cars on these new  roads from their suburban homes to work in the city. Some of the big car makers also bought the  electrified transportation systems and destroyed them. As people stopped using public  transporation , cities spent less money fixing old buses and trains or buying new ones. Public  transportation got worse and worse.       In the late 1960s, people found out that the increase in the use of cars led to many  problems. There were always too many cars for the highway system, and terrible traffic problems  developed. People were spending hours in traffic jams getting to and from work every day. In  addition, the air in many cities became dirty because of pollution from millions of cars, and many  people died in traffic accidents. As people began to get worried about how the use of cars was  hurting the environment,  cities began to spend more money on public transportation again,  so  fewer people would have to drive cars.       When gas became very expensive in the mid-1970s, the number of people taking public transportation  began to increase .It's terribly expensive to build new public transportation systems. so it's very difficult to make big changes in the way people travel .However ,an increase in the use of public transportation has begun. Why did some car companies buy and destroy  public transportation systems?
The system were slower than cars. The systems were too old to be fixed. They were trying to build better ones. They wanted to sell more of their products.