Final answer:
Progressive journalists who exposed corruption were called muckrakers. Their work was pivotal to the Progressive Era, involving the public in the call for reforms.
Step-by-step explanation:
The progressive journalists known for writing magazine articles exposing political and industrial corruption were called muckrakers. This term was coined by President Theodore Roosevelt, referencing a character from John Bunyan's The Pilgrim's Progress who was more interested in raking up muck than looking to heaven. Muckrakers became integral to the Progressive Era, highlighting issues such as corrupt machine politics, poor working conditions, and the living conditions of the working class. Their goal was to draw the public's attention to these issues, thereby spurring social reform and legislative action.