The article discusses how different factors influence states' decisions to adopt renewable portfolio standards (RPS) in the United States. Income, sensitivity to electricity prices, and the presence of merchant generators play a role in shaping RPS policies. States also focus on developing local renewable resources. This has led to varying RPS goals among states, with some pursuing ambitious targets at higher costs. The study suggests that relying solely on voluntary state support for renewables may not be a sustainable way to increase national renewable energy production.