What are the most common private bills proposed in congress?

Bills for permanent visas or citizenship

Explanation:

Private bills refers to the bill/law created by Congress which only applicable to specific individual or organization.

In united states, the most common private bills that create by congress revolved around obtaining citizenship. This happen because many people from across the globe (especially those from countries with lower standard of living) tend to see United states as one of their target destination to turn their lives around.