What role did muckrakers play in the progressive era? ?

Muckrakers brought the poverty in urban neighborhoods to the spotlight in hopes that once the middle/upper class are not turning a blind eye and become more aware of urban problems, more support would be given to government reforms that will solve the problems led on from the gilded age, such as corruption and poor working and living conditions for many poor immigrants. Muckrakers were successful in bringing positive changes, such as curtailing corruption of political machines such as Tammany Hall (Boss Tweed and muckraking journalist Thomas Nast) and increasing the public's voice in government through initiative, referendum, and recall.

Democracy and darwinism would be my answer.