September 14, 1901- The 42-year-old Vice President, Theodore Roosevelt, is suddenly elevated to the White House when President McKinley dies from an assassin's bullet.

October 12, 1901 - U.S. President Theodore Roosevelt renamed the Executive Mansion "The White House."

October 29, 1901 - President William McKinley's assassin, Leon Czolgosz, was electrocuted.

November 9, 1901 - President Theodore Roosevelt establishes a naval base in the Philippines at Subic Bay, on territory won from Spain during the Spanish-American War. He believed that the spot should become the Navy’s Pacific headquarters, as the area’s rugged jungle terrain would provide an ideal training ground for naval and marine forces. Roosevelt also viewed a major naval base in the Philippines as a critical strategic asset in light of Japan’s growing military might in the Pacific region and increasing political unrest in China. However, opposition from Leonard Wood, governor-general of the Philippines, and various military leaders, who preferred to build up an already existing base at Cavite in the Philippines, eventually derailed Roosevelt’s plans to move the Navy’s headquarters to Subic Bay. Roosevelt, disgusted with the hostile opposition of the military brass and Governor Wood, abandoned the idea in 1907. He then turned his attention to another potential site for an expanded naval base: Pearl Harbor, in Hawaii. After the Second World War, Subic Bay’s strategic importance was recognized. The harbor became a service port for U.S. forces during the Vietnam War. The base was eventually abandoned and the area was returned to the Filipino government in 1992.

November 27, 1901 - The Army War College was established in Washington, DC.

December 3, 1901 - President Theodore Roosevelt took the House floor to deliver a 20,000-word consideration of business conglomerations. Roosevelt called on Congress to curb the nation's trusts, though he urged the need for legislation that stayed "within reasonable limits"; sought policy which balanced free market principles with the "best interests" of the American public, allowing trusts to exist, within carefully measured limits.

December 10, 1901 - Nobel prizes were first awarded, in Oslo, Norway.

March 6, 1902 - Congress established a permanent "Census Office" in the Interior Department to carry out a continuing program of censuses and other data collection activities; July 1902 - about 900 workers finished the 1900 census (U.S. population of 80 million) in a nondescript building near the U.S. Capitol, became permanent federal employees; 1903 - Bureau of the Census was transferred to the new Department of Commerce and Labor; 1913 - Labor Department split from Commerce, the bureau continued with the Commerce Department, where it remains today; April 1, 2000 (Census Day) - U.S. population of 281 million.

May 31, 1902 - In Pretoria, representatives of Great Britain and the Boer states sign the Treaty of Vereeniging, officially ending the three-and-a-half-year South African Boer War. Treaty recognized the British military administration over Transvaal and the Orange Free State, and authorized a general amnesty for Boer forces. Boers, also known as Afrikaners, were the descendants of the original Dutch settlers of southern Africa. 1806 - Britain took possession of the Dutch Cape colony during the Napoleonic wars, sparked resistance from the independence-minded Boers, who resented the Anglicization of South Africa and Britain's anti-slavery policies. 1833 - Boers began an exodus into African tribal territory, where they founded the republics of the Transvaal and the Orange Free State. 1867 - discovery of diamonds and gold in the region made conflict between the Boer states and Britain inevitable.

June 28, 1902 - Panama Canal (Spooner) Act of 1902 - agreed to pay $40 million for the rights and properties of Compagnie Universelle du Canal Interoceanique, 1881, and by Compagnie Nouvelle du Canal de Panama, 1894; U. S. paid $10 million to the Republic of Panama for the use of the land. The U.S. engineers and medical doctors were more successful than the French and the Panama Canal opened for traffic on August 15, 1914.

March 10, 1902 - Attorney General Philander Knox filed an anti-trust suit against J. P. Morgan's Northern Securities Company; case revolved around whether or not Northern Securities, New Jersey-based holding concern for Morgan's western railroad business, violated Sherman Anti-Trust Act; early 1904 - Supreme Court ruled against Northern Securities, handed Theodore Roosevelt and Knox high-profile victory in war on trusts.

May 20, 1902 - The United States ended its occupation of Cuba.

August 9, 1902 - Edward VII was crowned king of England following the death of his mother, Queen Victoria.

August 22, 1902 - President Theodore Roosevelt became the first U.S. President to ride in an automobile, in Hartford, CT.

February 11, 1903 - Congress passed Expedition Act,  prioritized anti-trust suits filed in the nation's circuit courts; under Theodore Roosevelt, Justice Department filed forty-five anti-trust suits; Roosevelt also led the successful crusade to break up Standard Oil's monopoly (1907); earned Roosevelt a sterling reputation as a tough-talking "trust-buster"; viewed "bigness" as a fait accompli; trust-busting stance was borne of political expediency, desire to preserve the government's tacit regulatory control of corporate America.

February 14, 1903 - Congress followed the lead of President Theodore Roosevelt and passed legislation which created the Department of Commerce and Labor and the Bureau of Corporations (predecessor to the Federal Trade Commission as an investigatory agency); charged with probing into the activities of corporations involved in interstate trade; another visible symbol of Roosevelt's campaign to clamp down on business corruption. The legislation," Roosevelt wrote in response to his critics, "was moderate. It was characterized throughout by the idea that we were not attacking corporations, but endeavoring to provide for doing away for any evil in them."

February 23, 1903 - U.S. government obtained a perpetual lease from Tomás Estrada Palma, an American citizen, who became the first President of Cuba; The newly formed American protectorate incorporated the Platt Amendment in the Cuban Constitution. The Cuban-American Treaty held, among other things, that the United States, for the purposes of operating coaling and naval stations, has "complete jurisdiction and control" of the Guantánamo Bay, while the Republic of Cuba is recognized to retain ultimate sovereignty; December 10, 1903 - Guantánamo Bay Naval Station leased to the U.S.; December 10, 1913 - Naval station officially opens; May, 31, 1934 - treaty reaffirming the lease granted Cuba and her trading partners free access through the bay, modified the lease payment from $2,000 in U.S. gold coins per year, to the 1934 equivalent value of $4,085 in U.S. Treasury Dollars, and added a requirement that termination of the lease requires the consent of both governments, or the abandonment of the base property by the United States; United States holds that by cashing the first check received in accordance with said treaty, Castro's government effectively ratified the lease, and cannot unilaterally change its mind after the fact on account of political tensions or ideological differences; April 1, 1941 - renamed Guantánamo Bay U.S. Naval Operating base.

March 14, 1903 - President Theodore Roosevelt established the first US national bird sanctuary by executive order; protected the nesting colony of pelicans and herons on Pelican Island, FL.

May 12, 1903 - President Theodore Roosevelt’s trip to San Francisco is captured on moving-picture film, making him the first president to have an official activity recorded in that medium. cameraman named H.J. Miles filmed the president while riding in a parade in his honor. The resulting short move was titled The President’s Carriage and was later played on "nickelodeons" in arcades across America. The film showed Roosevelt riding in a carriage and escorted by the Ninth U.S. Cavalry Regiment, which was unusual for the time, according to the Library of Congress and contemporary newspapers, because it was an all-black company.

July 4, 1903 - President Theodore Roosevelt sent the first official message over the new cable across the Pacific Ocean between Honolulu, Midway, Guam and Manila.

October 20, 1903 - A joint commission ruled in favor of the United States in a boundary dispute between Alaska and Canada.

November 3, 1903 - Panama proclaimed its independence from Colombia; November 6, 1903 - United States recognized the Republic of Panama (independent of Colombia); November 18, 1903 - the Hay-Bunau-Varilla Treaty was signed with Panama, granted the U.S. exclusive and permanent possession of the Panama Canal Zone. In exchange, Panama received $10 million and an annuity of $250,000 beginning nine years later. The treaty was negotiated by U.S. Secretary of State John Hay and Bunau-Varilla, who had been given plenipotentiary powers to negotiate on behalf of Panama.

February 8, 1904 - Following the Russian rejection of a Japanese plan to divide Manchuria and Korea into spheres of influence, Japan launched a surprise naval attack against Port Arthur, a Russian naval base in China; Russian fleet was decimated.

February 23, 1904 - U.S. acquired control of the Panama Canal Zone for $10 million. 1903 - Panama declared its independence from Colombia in a U.S.-backed revolution; November 18, 1803 -  U.S. and Panama signed the Hay-Bunau-Varilla Treaty, also called "The Treaty No Panamanian Signed" (Secretary of State John Hay and Philippe Jean Bunau-Varilla of the Compagnie Nouvelle du Canal de Panama, which still had the concession, as well as certain valuable assets, for the building of a canal in Panama), in which the U.S. agreed to pay Panama $10 million for a perpetual lease on land for the canal, plus $250,000 annually in rent.

May 14, 1904 - The first Olympic games to be held in the United States opened in St. Louis. 1904 Games were actually initially awarded to Chicago, IL, but were later given to St. Louis to be staged in connection with the St. Louis World Exposition. Like the Second Olympiad, held in Paris in 1900, the St. Louis Games were poorly organized and overshadowed by the world's fair. There were few entrants other than Americans in the various events, and, expectedly, U.S. athletes won a majority of the competitions and the unofficial team championship. In the field events, the Americans made a near-perfect sweep, winning everything but lifting the bar and throwing the 56-pound weight. Twenty years later, the first truly successful Olympic Games were held in Paris, and since then, with increasing popularity, the games have been held in various cities around the globe.

September 1, 1904 - St. Petersburg Telegraph Agency (SPTA), first official news agency of Russia began; August 19, 1914 - one day after Nicholas the Second ruled to rename St. Petersburg into Petrograd, SPTA changed its name to Petrograd Telegraph Agency (PTA); September 7, 1918 - government presidium resolved to rename PTA and the Press bureau into the Russian Telegraph Agency (ROSTA); July 10, 1925 - Telegraph Agency of the Soviet Union (TASS) was founded, took over the main functions of the Russian Telegraph Agency as the central information agency of the country; 1992 - renamed ITAR-TASS News Agency when Russia proclaimed its sovereignty following the collapse of the USSR; retained its status of being the state central information agency.

October 20, 1904 - Bolivia and Chile signed a treaty ending the War of the Pacific.

November 8, 1904 - President Theodore Roosevelt (R) defeats Alton B. Parker (D-NY), judge of New York Court of Appeals from 1898 to 1904.

January 2, 1905 - Japanese Gen. Nogi received a letter from Russian Gen. Stoessel formally offering to surrender after strategic naval base of Port Arthur, major Russian naval base on the Liaodong Peninsula in China, fell to the Japanese naval and ground forces under Admiral Heihachiro Togo. Probable that the back of the Russian defense was broken when 203-Meter Hill was captured. The Russians desperately sought to retake that eminence, and sent infantry and marines against it in a series of counter-attacks, fruitlessly losing thousands of men. March 1905 - Russian troops were defeated at Shenyang, China, by Japanese Field Marshal Iwao Oyama; May 27, 1905 - Russian Baltic fleet under Admiral Zinovi Rozhdestvenski was destroyed by Togo near the Tsushima Islands in Battle of Tsushima Strait (only 10 of 45 Russian warships escaped to safety). Roosevelt later awarded the Nobel Peace Prize for brokering peace.

January 22, 1905 - The first Russian Revolution began when czarist troops opened fire on a peaceful group of workers marching to the Winter Palace in St. Petersburg to petition their grievances to Czar Nicholas II. It became known as "Bloody Sunday"; Russian troops opened fire on workers (led by the radical priest Georgy Apollonovich Gapon) marching to the czar's Winter Palace in St. Petersburg to petition their grievances to Czar Nicholas II; some 500 protestors were massacred; set off months of protest and disorder throughout Russia; decade later, czarist Russia was bogged down in the mire of World War I, prompting the Bolshevik-led Russian Revolution of 1917, which crushed the czar's opposition and proclaimed Russia the world's first Marxist state.

February 13, 1905 - President Theodore Roosevelt delivers a stirring speech to the New York City Republican Club. Roosevelt had just won his second reelection, and in this speech, he discussed the country’s current state of race relations and his plan for improving them. Roosevelt’s solution to the race problem in 1905 was to proceed slowly toward social and economic equality. He cautioned against imposing radical changes in government policy and instead suggested a gradual adjustment in the attitudes of whites toward ethnic minorities. He referred to white Americans as "the forward race," whose responsibility it was to raise the status of minorities through training "the backward race[s] in industrial efficiency, political capacity and domestic morality." Thus, he claimed whites bore the burden of "preserving the high civilization wrought out by its forefathers." His administration took only a passive, long-term approach to improving civil rights.

March 4, 1905 - Theodore Roosevelt was sworn in for his second term as president.

March 31, 1905 - Kaiser Wilhelm of Germany arrives in Tangiers to declare his support for the sultan of Morocco, provoking the anger of France and Britain in what will become known as the First Moroccan Crisis, a foreshadowing of the greater conflict between Europe’s great nations still to come, the First World War. The Kaiser did not have any substantive interest in Morocco; neither did the German government. The central purpose of his appearance was to disrupt the Anglo-French Entente, formed in April 1904. The Entente Cordiale, as it was known, was originally intended not as an alliance against Germany but as a settlement of long-standing imperialist rivalries between Britain and France in North Africa. By its terms, Britain could pursue its interests in Egypt, while France was free to expand westward from Algeria into Morocco, the last territory that remained independent in the region. Germany believed that the Anglo-French Entente went a long way towards the creation of a new diplomatic balance in Europe. posed a challenge to Germany’s own influence in Europe and the world.

September 1, 1905 - Alberta and Saskatchewan became the eighth and ninth provinces of Canada.

September 5, 1905 - President Theodore Roosevelt mediated The Treaty of Portsmouth, ending the Russo-Japanese War, signed in New Hampshire. Russia recognized Japan as the dominant power in Korea and gave up Port Arthur, the southern half of Sakhalin Island, and the Liaotung Peninsula to Japan. Japan emerged from the conflict as the first modern non-Western world power.

October 26, 1905 - Sweden and Norway ended their union and Oscar II, the Norwegian king, abdicated.

October 30, 1905 - The Russian czar issued the October Manifesto, which granted civil liberties and elections in hopes of averting a revolution.

November 28, 1905 - Irish nationalist Arthur Griffith founded Sinn Féin (Gaelic for "we ourselves" but also for "ourselves alone"), a political party dedicated to independence for all of Ireland, in Dublin; became the unofficial political wing of militant Irish groups in their struggle to throw off British rule. In 1911, the British Liberal government approved negotiations for Irish Home Rule, but the Conservative Party opposition in Parliament, combined with Ireland's anti-Home Rule factions, defeated the plans. With the outbreak of World War I, the British government delayed further discussion of Irish self-determination, and Irish nationalists responded by staging Dublin's Easter Uprising of 1916. In 1918, with the threat of conscription being imposed on the island, the Irish people gave Sinn Féin a majority in national elections, and the party established an independent Irish Parliament--Dáil Éireann--which declared Ireland a sovereign republic. In 1919, the Irish Volunteers, a prototype of the Irish Republican Army (IRA), launched a widespread and effective guerrilla campaign against British forces. In 1921, a cease-fire was declared, and in 1922 Arthur Griffith and a faction of former Sinn Féin leaders signed a historic treaty with Britain, calling for the partition of Ireland, with the south becoming autonomous and the six northern counties of the island remaining in the United Kingdom. Civil war followed the partition, ending with the defeat of the Irish Republican forces in 1923 by the Irish Free State (later the Republic of Ireland). Several years later, the IRA was reorganized underground. During the next eight decades, Sinn Féin remained the unofficial political wing of the IRA in its struggle for a unified and independent Ireland.

February 1, 1906 - First federal penitentiary building completed, Leavenworth, Kansas.

April 11, 1906 - Albert Einstein introduces his Theory of Relativity.

April 14, 1906 - President Theodore Roosevelt first used the term "muck-rake" as he criticized what he saw as the excesses of investigative journalism in a speech at the laying of the corner stone of the Cannon Office Building in Washington, DC (most famous: Lincoln Steffens, Ida Tarbell, Edward Markham, David Graham Phillips, Ray Stannard Baker Samuel Hopkins Adams, Upton Sinclair, Jacob Riis, Henry Demarest Lloyd, Brand Whitlock); taken from the fictional character in John Bunyan's Pilgrim's Progress, a man who was consigned to rake muck endlessly, never lifting his eyes from his drudgery.

April 18, 1906 - Major earthquake struck San Francisco and set off raging fires. More than 3,000 people died. The first of two vicious tremors shook San Francisco at 5:13 a.m., and a second followed not long after. Thousands of structures collapsed as a result of the quake itself. However, the greatest devastation resulted from the fires that followed the quake. The initial tremors destroyed the city's water mains, leaving overwhelmed firefighters with no means of combating the growing inferno. The blaze burned for four days and engulfed the vast majority of the city. More than 28,000 buildings burned to the ground and the city suffered more than $500 million in damages. The human toll was equally disastrous: authorities estimated that the quake and fires killed 700 people, and left a quarter of a million people homeless. The famous writer and San Francisco resident Jack London noted, "Surrender was complete." During the next four years, the city arose from its ashes. Ironically, the destruction actually allowed city planners to create a new and better San Francisco. A classic western boomtown, San Francisco had grown in a haphazard manner since the Gold Rush of 1849. Working from a nearly clean slate, San Franciscans could rebuild the city with a more logical and elegant structure. The destruction of the urban center at San Francisco also encouraged the growth of new towns around the bay, making room for a new population boom arriving from the U.S. and abroad. Within a decade, San Francisco had resumed its status as the crown jewel of the American West.

June 8, 1906 - Congress enacted the American Antiquities Act of 1906; permitted President to declare by public proclamation historic landmarks, historic and prehistoric structures, and other objects of historic or scientific interest that are situated upon the lands owned or controlled by the Government of the United States to be national monuments.

June 30, 1906 - President Roosevelt signed Federal Food and Drugs Act of 1906 (The "Wiley Act") became law (Meat Inspection Act was a companion measure with the Pure Food and Drug Act); prevented the manufacture, sale, or transportation of adulterated or misbranded or poisonous or deleterious foods, drugs, medicines, and liquors, and for regulating traffic therein, and for other purposes. Named for Harvey W. Wiley came to be the leader of the "pure food crusade"; chemist and physician, State chemist of Indiana and professor at Purdue University, Wiley went to Washington in 1883 as chief chemist of the Department of Agriculture. He made the study of food adulteration his bureau's principal business, at first merely outraged by what he deemed essentially harmless fraud. In time, sensing real threats to health, Wiley could express himself in writing, conversation, and oratory with vividness, clarity, homely wit, and moral passion. He toured the country making speeches, every rostrum a pulpit for the gospel of pure food. Passage of Meat Inspection Act was aided by the publication of Upton Sinclair's famous novel, The Jungle (1906) - revealed in ghastly detail the unsanitary conditions of the Chicago stockyards and meat-packing plants.

July 6, 1906 - Second Geneva Convention. Principles of the Geneva Convention adapted to Maritime War at the Convention for the Amelioration of the Condition of the Wounded and Sick in Armies in the Field in Geneva.

September 24, 1906 - President Theodore Roosevelt signed a bill designating Devils Tower, a natural rock formation in the Black Hills of Wyoming, as the country's first National Monument.

November 9, 1906 - President Theodore Roosevelt makes first foreign trip by a U.S. president, to inspect progress on the Panama Canal, aboard the battleship Louisiana; traveled to the U.S. territory of Puerto Rico, returned to the United States on November 26.

November 30, 1906 - President Theodore Roosevelt denounced segregation of Japanese schoolchildren in San Francisco. 

December 10, 1906 - President Theodore Roosevelt became the first American to be awarded the Nobel Peace Prize, for helping mediate an end to the Russo-Japanese War.

January 26, 1907 - Congress passed a reform bill that barred America's corporations from making contributions to national campaigns.

November 16, 1907 - Oklahoma became the 46th state of the Union; name derived from the Choctaw Indian words okla, meaning "people," and humma, meaning "red"; 1907 - Congress decided to admit Indian Territory and Oklahoma Territory into the Union as a single state, with all Indians in the state becoming U.S. citizens. Representatives of the two territories drafted a constitution; September 17, 1907 - it was approved by voters of the two territories.

January 9, 1908 - President Theodore Roosevelt signed Proclamation of Muir Woods National Monument (in accordance with Antiquities Act of 1906), consisting of 295 acres. Muir Woods becomes the 7th National Monument, first created from land donated by a private individual (1905 - William Kent and his wife Elizabeth Thacher Kent acquired 611 acres, "Sequoia Canyon", from Tamalpais Land and Water Company for discounted sum of $45,000.

January 11, 1908 - President Theodore Roosevelt designates the mighty Grand Canyon a national monument; declares that "The ages had been at work on it, and man can only mar it"; 1932 - Congress increased the protection of the canyon, made it a national park.

February 1, 1908 - King Carlos I of Portugal and his eldest son, Luis Filipe, are assassinated by revolutionaries while riding in an open carriage through the streets of Lisbon, the Portuguese capital. Widespread criticism of Joao Franco's dictatorial regime led to a revolt in early 1908. Carlos' second son, Manoel, succeeded him to the throne; October 1910 - a republican revolution forced King Manoel II to abdicate and flee to England with the rest of the royal family. In the same year, Teofilo Braga, a well-known writer, was chosen the first president of the newly democratic republic of Portugal.