Smith ran for mayor in 1917 on an anti-corruption platform. Louisville's dominant political boss for three decades, John Henry Whallen, had died in 1913 and his less charismatic brother was unable to use the party's political machine to defeat Smith. Smith followed through on election promises, shutting down brothels and gambling along the then-seedy Green Street. After the Louisville Herald drummed up public interest with a naming contest, the Republican-majority city council gave the street its modern name, Liberty Street, in 1918. He also ordered the Louisville Police Department to assist federal agents in enforcing Prohibition.
The administration soon focused on the World War I effort, with Smith himself involved in war bond drives. Camp Zachary Taylor, one of the largest training camps built for the war effort, was located at was then the edge of the city.
The city grew 40 percent in size during his administration through the annexation of surrounding areas. After his term as mayor, he served as president of the Louisville Water Company until 1926.