George B. McClellan, Jr. was born in Dresden (later to become Germany) in 1865. Son of the infamous Civil War General of the same name, he grew up in New Jersey and graduated from Princeton in 1886.
In the 1890s, McClellan served on the Board of Aldermen of the City of New York, becoming President in 1893. In 1894, during a leave of absence from Mayor Thomas Gilroy's term, McClellan served as Acting Mayor for a few months. His political career then led him to represent New York in the U.S. House of Representatives. McClellan was elected as a Tammany Hall candidate in 1904, ousting Seth Low.
McClellan served as Mayor for six years, successfully beating William Randolph Hearst's candidacy in 1905. McClellan presided over many significant changes and developments in New York City history, including the opening of the first subway line, the opening of the Williamsburg Bridge, the christening of Times Square, and the opening of the Battery Maritime Terminal. By the time his tenure ended, the New York Public Library was nearly finished, Grand Central was under construction, and Manhattan Bridge was on its way to completion. He presided over construction of Chelsea Piers, further strengthening New York's position as a world port. McClellan also famously tore up the licenses of over 550 motion picture exhibitors, possibly because early movies were seen as related to vice.
Late in his administration, McClellan moved away from Tammany politics, a move that was a possible contributor to losing his Mayoral re-election campaign. After the end of his political career, he taught at Princeton until 1931. He died in 1940 in Washington, DC.