Mayor Tucker ran for re-election successfully in 1957. He backed the proposed City Charter that was defeated August 6, 1957. The increase in the Earnings Tax from one-half percent to one percent became effective August 1, 1959. He opposed the Metropolitan District Plan of 1959 and the Borough Plan of 1962; each would have restructured the relationship between St. Louis City and St. Louis County. He became president of the American Municipal Association (now the National League of Cities) in 1959 and headed the United States Conference of Mayors from December 1963 to April 20, 1965. The City Charter was amended in August 1960 to raise the City salary limit from $10,000 to $25,000. In 1956, the mayor had appointed a committee of building industry people to draw up a new Building Code, which he signed into law on March 31, 1961.