The American Association of Retired Persons (AARP) is an example of an interest group or lobbying group.
The AARP functions as an NGO in the sense that it does not seek to earn economic profit, but to influence public opinion and political decisions, with the ultimate aim of empowering US citizens so that they can dedide how they want to live as they age. In 2018 it counted with more than 38 millions members and a very important lobbying power.