Car crashes are extremely dangerous. In the past, not all cars had seat belts. As highways began
to spread across the United States, more and more people were getting hurt in car crashes. The
government made a new law requiring everyone to wear a seatbelt in order to keep people safe.
As a result, there were far fewer deaths on the road. It was estimated that seatbelts saved about
14,000 lives in the year 2015.
What is the structure?