FACTBOX: The first 100 days of a U.S. presidency

(Reuters) - Assessing a new U.S. president's first 100 days in office has become an American media tradition which historians trace to the initial burst of activity at the start of Democrat Franklin Roosevelt's tenure in 1933.

- Roosevelt's "First 100 Days" -- described as a "Defining Moment" for America by author Jonathan Alter -- was a time of struggle and renewal. Some analysts say President-elect Barack Obama faces such a time in the worst financial crisis since.

- The two men, both Democrats, took office promising change at a time of crisis. Both had strong majorities in both houses of Congress. Like Roosevelt, Obama's presidency will begin after years of bitter partisan politics.

- Obama's stated goals include the protection or creation of 3 to 4 million jobs with a combination of middle-class tax cuts, money for public works programs and money to bolster national health and other social programs.

- Harvard academic John Stauffer says differences have already emerged with Obama far more active, at least in his statements, than Roosevelt was in the months before taking office.