Photos: Michael Bloomberg

Running for Mayor
In 2001, Bloomberg entered the world of politics, running for Mayor of New York when Rudolph Giuliani's second and last term ended. A registered Democrat, Bloomberg (right, with Giuliani during that year's Columbus Day parade) switched his party affiliation to run on the Republican ticket because of the already crowded Democratic field. Despite the many who doubted him, Bloomberg succeeded and won the election. On November 6, 2001 he became the city's 108th mayor.