The main motivation was to reduce the power of political bosses, who controlled the Senate seats by virtue of their control of state legislatures. States started using primary elections to reduce the power of machines and bosses. The Seventeenth Amendment was ratified in 1913, requiring that all senators be elected by the people.
This era is well known for the expansion in the number of schools and students served. After 1910 the cities began building schools. The "Flexner