Title: Timeline of the Theodore Roosevelt presidency
Content:  The presidency of Theodore Roosevelt began on September 14, 1901, when Theodore Roosevelt was inaugurated as the 26th president of the United States, and ended on March 4, 1909.
Title: Timeline of the Theodore Roosevelt presidency
Content: March 4 - Inauguration of William Howard Taft 
Title: 59th United States Congress
Content: March 4, 1905: President Theodore Roosevelt began his second (only full) term. 
Title: First inauguration of Theodore Roosevelt
Content:  The first inauguration of Theodore Roosevelt as the 26th president of the United States, took place on Saturday, September 14, 1901, at the Ansley Wilcox House, at 641 Delaware Avenue in Buffalo, New York, following the death of President William McKinley earlier that day. The inauguration – the fifth non-scheduled, extraordinary inauguration to ever take place and the first in the 20th century – marked the commencement of the first term (a partial term of 3 years, 172 days) of Theodore Roosevelt as president. John R. Hazel, U.S. District Judge for the Western District of New York, administered the presidential oath of office.
Title: Timeline of the Theodore Roosevelt presidency
Content: March 4 - Second inauguration of Theodore Roosevelt ; September 5 -  The Treaty of Portsmouth is signed ; February 1 - The National Forest Service is established ; June 27 - The Industrial Workers of the World is established in Chicago 
Title: Timeline of the Theodore Roosevelt presidency
Content: February 8 - The Russo-Japanese War begins ; May 4 - The United States takes over construction of the Panama Canal 
Title: Second inauguration of Theodore Roosevelt
Content:  The second inauguration of Theodore Roosevelt as president of the United States, took place on Saturday, March 4, 1905, at the East Portico of the United States Capitol in Washington, D.C. This was the 30th inauguration and marked the beginning of the second and only full term of Theodore Roosevelt as president and the only term of Charles W. Fairbanks as vice president. Chief Justice Melville Fuller administered the presidential oath of office.
Title: Theodore Roosevelt
Content:  Theodore Roosevelt Jr. (October 27, 1858 – January 6, 1919), often referred to as Teddy or his initials T. R., was an American politician, statesman, conservationist, naturalist, historian, and writer who served as the 26th president of the United States from 1901 to 1909. He previously served as the 25th vice president under William McKinley from March to September 1901, and as the 33rd governor of New York from 1899 to 1900. Having assumed the presidency after McKinley's assassination, Roosevelt emerged as a leader of the Republican Party and became a driving force for anti-trust and Progressive policies. Roosevelt was 
Title: Presidency of Franklin D. Roosevelt, first and second terms
Content:  The first term of the presidency of Franklin D. Roosevelt began on March 4, 1933, when he was inaugurated as the 32nd president of the United States, and the second term of his presidency ended on January 20, 1941, with his inauguration to a third term. Roosevelt, the Democratic governor of the largest state, New York, took office after defeating incumbent President Herbert Hoover, his Republican opponent in the 1932 presidential election. Roosevelt led the implementation of the New Deal, a series of programs designed to provide relief, recovery, and reform to Americans and the American economy during the Great Depression. He 
Title: Presidency of Theodore Roosevelt
Content:   Roosevelt served as assistant secretary of the navy and governor of New York before winning election as William McKinley's running mate in the 1900 presidential election. Roosevelt became president following the assassination of McKinley by anarchist Leon Czolgosz in Buffalo, New York; Czolgosz shot McKinley on September 6, 1901, and McKinley died on September 14. Roosevelt was sworn into office on the day of McKinley's death at the Ansley Wilcox House in Buffalo. John R. Hazel, U.S. District Judge for the Western District of New York, administered the oath of office. Being just a few weeks short of his 43rd birthday, Roosevelt became the youngest president in U.S. history, a distinction he still retains. When 

Question: when did president theodore roosevelt take office?
Answer: 9/14/1901.