Public goods can be shared by everyone, but some can be controlled or not. A study looked at how these different types of public goods affect economic growth. They found that congestion plays a big role in deciding how to pay for these goods. Depending on how crowded things get, the government might not have enough money to cover all the costs. They also looked at how the government could charge people to use these goods. The study used different ways of making things to see how they affect growth.