Missouri Governor. As an attorney for the Amalgamated Association of Street Railway Employees in its struggle against the St. Louis Transit Company in 1900, his poltical ambitions were ignited. He was elected circuit attorney for St. Louis in 1900 and participated in a series of municipal investigations. Bribes were uncovered in connection with street railway and garbage company franchises that resulted in several trials and convictions, including that of St. Louis boss Edward Butler. He also assisted the state attorney general in the investigation of bribes involving the state legislature. These investigations, prosecutions, and convictions gained him national attention and enabled him to win the Democratic nomination for Governor of Missouri in 1904. He was elected with 52% of the vote. As governor, he was known as a progressive reformer. His administration reflected on the state level many of the reforms that were advocated nationally by President Theodore Roosevelt. His reforming zeal earned him the nickname "Holy Joe." A compulsory education bill, a child labor bill, an eight hour labor bill in mines and smelters, and a maximum hour law for railway workers were passed. He successfully pushed for a Sunday closing law, restrictions on race track gambling, anti-lobbying legislation, a direct primary election law, a pure food act, and the submission of the iniative and referendum for popular approval. His extensive reform program became known as the "Missouri Idea" and gained him national attention as well as the antipathy of the state's vested interests. State law limited him to only one term and he left office as a relatively young man in 1909. Having split from the machine and establishment elements within his party, his efforts to achieve further political offices were frustrated. He toured as a lecturer and advocate for reform and progressive causes. His aggressive reform record made him a potential candidate for the Democratic nomination for President of the United States in 1912, but he withdrew in favor of his fellow Missourian Speaker of the House Champ Clark. Ultimately, he enthusiastically supported Woodrow Wilson for the Presidency in 1912. Wilson appointed him solicitor general of the State Department in 1912 and chief counsel for the Interstate Commerce Commission in 1914. He ran unsuccessfully for the United States Senate in 1918 and resumed a private law practice in Washington D. C. in 1919. In March of 1922, he suffered a severe nervous breakdown from which he never recovered.

Missouri Governor. As an attorney for the Amalgamated Association of Street Railway Employees in its struggle against the St. Louis Transit Company in 1900, his poltical ambitions were ignited. He was elected circuit attorney for St. Louis in 1900 and participated in a series of municipal investigations. Bribes were uncovered in connection with street railway and garbage company franchises that resulted in several trials and convictions, including that of St. Louis boss Edward Butler. He also assisted the state attorney general in the investigation of bribes involving the state legislature. These investigations, prosecutions, and convictions gained him national attention and enabled him to win the Democratic nomination for Governor of Missouri in 1904. He was elected with 52% of the vote. As governor, he was known as a progressive reformer. His administration reflected on the state level many of the reforms that were advocated nationally by President Theodore Roosevelt. His reforming zeal earned him the nickname "Holy Joe." A compulsory education bill, a child labor bill, an eight hour labor bill in mines and smelters, and a maximum hour law for railway workers were passed. He successfully pushed for a Sunday closing law, restrictions on race track gambling, anti-lobbying legislation, a direct primary election law, a pure food act, and the submission of the iniative and referendum for popular approval. His extensive reform program became known as the "Missouri Idea" and gained him national attention as well as the antipathy of the state's vested interests. State law limited him to only one term and he left office as a relatively young man in 1909. Having split from the machine and establishment elements within his party, his efforts to achieve further political offices were frustrated. He toured as a lecturer and advocate for reform and progressive causes. His aggressive reform record made him a potential candidate for the Democratic nomination for President of the United States in 1912, but he withdrew in favor of his fellow Missourian Speaker of the House Champ Clark. Ultimately, he enthusiastically supported Woodrow Wilson for the Presidency in 1912. Wilson appointed him solicitor general of the State Department in 1912 and chief counsel for the Interstate Commerce Commission in 1914. He ran unsuccessfully for the United States Senate in 1918 and resumed a private law practice in Washington D. C. in 1919. In March of 1922, he suffered a severe nervous breakdown from which he never recovered.