In the article, they looked at why certain industries end up in specific areas. They studied the early U.S. car industry and found two main reasons for this: the benefits companies get from being close to each other and the new companies that pop up because of existing companies (spinoffs). They found that both of these reasons help industries group together, with existing benefits having a bigger impact. This means that when a local economy and related industries support new companies, it leads to more businesses forming in one area. Spinoff companies also add to this effect but become more important as the industry grows.