Most interest groups are founded on the basis of a shared ideology or position among a group of people who wish to express their collective stance to the general public, the government or an organization, trying to keep their issues relevant. The ability to form interest groups and convey collective opinions is derived from democratic principles, including the rights to free speech and to appeal to governing bodies.
The heterogeneous nature of the 20th century United States and the acknowledgement of this fact by both individuals and organizations led to an explosion of interest groups, especially during the latter half of the 1900s. The levels of religious, ethnic, economic, geographic, cultural and climatic diversity, among others, create socioeconomic, cultural and political fault lines as they near one another. Numerous groups and movements develop as a result.
Interest groups exist to exert some type of influence on legal and political structures and typically have profound effects on economics and budgeting, moral and ethical values promoted by citizens and governing bodies, political processes and legislative efforts at every level of American society. Groups may have only one issue they are pushing or several. They either represent concerned individuals or members of existing organizations or corporations trying to further their own causes