In the 1960s and 1970s, the U.S. witnessed a rise of public interest groups, due to the progressive spirit of the time where a good number of them established their offices after 1960 and opened their doors after 1970s. The interest groups comprised of: professional associations, public interest groups, business and agricultural groups, labor groups, ideological groups, and public-sector groups. Several factors determined the growth interest groups in the United States. First, The U.S. is heterogeneous in several aspects: its geography, climate, economic potential, culture, ethnicity, and religions. The heterogeneity resulted in political, socio-economic and cultural divisions which led to the evolution of several interest groups, each with unique objectives.
