[2] Early in his career, Folk ran for a seat in the Tennessee House of Representatives in 1892, wrote newspaper articles, spoke on special occasions, and joined the Knights of Pythias.

With the assistance of Lincoln Steffens's articles published in McClure's magazine, Folk led investigations of the city's Democratic boss, Col. Ed Butler and the corrupt "boodle ring" of corporate bribery in the state and municipal government.

Folk gained the respect of Republican President Theodore Roosevelt as he and other crusading prosecutors and muckraking journalists brought national attention to municipal corruption.

Folk's prosecution of the Suburban Railway Company stimulated a change in US treaties with Mexico to include bribery as grounds for extradition.

As district attorney, Folk encountered opposition from many businessmen and politicians, who believed that his exposing corrupt practices hurt the city's reputation, and thus the Democratic party as well as the business climate.

The governor was able to enact further legislation, including an initiative and referendum amendment to the Constitution of Missouri, and further regulation of elections, education, employment and child labor, railroads, food, business, and public utilities.

[2] Following his gubernatorial term, Folk's focus on morality and unwillingness to compromise eventually made him politically unpopular, and his initial attempts for a senate nomination were unsuccessful.