9th January » Hallam Tennyson, 2nd Baron Tennyson, son of the poet Alfred, Lord Tennyson or Alfred Tennyson, becomes the second Governor-General of Australia.
17th January » El Yunque National Forest in Puerto Rico becomes part of the United States National Forest System as the Luquillo Forest Reserve.
14th February » The United States Department of Commerce called United States Department of Commerce and Labor is established (later split into the Department of Commerce and the United States Department of Labor named Department of Labor).
23rd February » Cuba leases Guantanamo Bay Naval Base e.g Guantánamo Bay to the United States "in perpetuity".
2nd March » In New York City the Martha Washington Hotel opens, becoming the first hotel exclusively for women.
14th March » The Hay–Herrán Treaty, granting the United States the right to build the Panama Canal, is ratified by the United States Senate. The Colombian Senate would later reject the treaty.
14th March » The Pelican Island National Wildlife Refuge is established by US President Theodore Roosevelt.
31st March » Richard Pearse allegedly makes a powered flight in an early aircraft.
19th April » The Kishinev pogrom in Kishinev (Bessarabia) begins, forcing tens of thousands of Jews to later seek refuge in Palestine and the Western world.
29th April » A 30 million cubic-metre Frank Slide e.g landslide kills 70 in Frank, Alberta named Frank, North-West Territories, Canada.
22nd May » Launch of the White Star Liner, SS known as Ionic.
11th June » A group of Serbian officers May Coup (Serbia) stormed royal palace and assassinated King Alexander I of Serbia Alexander Obrenović and his wife queen Draga Obrenović Draga.
16th June » The Ford Motor Company is incorporated.
16th June » Roald Amundsen commences the first east-west navigation of the Northwest Passage, leaving Oslo, Norway.
1st July » Start of 1903 Tour de France called first Tour de France Bicycle racing e.g bicycle race.
4th July » Philippine–American War officially is concluded.
9th July » Future Soviet dictator Joseph Stalin is exiled to Siberia for three years.
19th July » Maurice Garin wins the 1903 Tour de France e.g first Tour de France.
20th July » The Ford Motor Company ships its first car.
21st July » Battle of Ciudad Bolívar, a victory of federal army of Juan Vicente Gómez over forces of general Nicolás Rolando.
23rd July » The Ford Motor Company sells its first car.
2nd August » Fall of the Ottoman Empire: an unsuccessful uprising led by the Internal Macedonian Revolutionary Organization against Ottoman Empire e.g Ottoman Turkey, also known as the Ilinden–Preobrazhenie Uprising, takes place.
3rd August » Internal Macedonian Revolutionary Organization e.g Macedonian rebels in Kruševo proclaim the Kruševo Republic, which exists only for 10 days before Ottoman Empire known as Ottoman Turks lay waste to the town.
18th August » German engineer Karl Jatho allegedly flies his self-made, motored gliding airplane four months before the first flight of the Wright brothers.
29th August » The ship Russian battleship Slava 2, the last of the five sclass- Borodino battleships, is launched.
11th September » The first race at the Milwaukee Mile in West Allis, Wisconsin is held. It is the oldest major speedway in the world.
27th September » Wreck of the Old 97, a train crash made famous by the song of the same name.
1st October » Baseball: The Boston Americans play the Pittsburgh Pirates in the first game of the modern World Series.
6th October » The High Court of Australia sits for the first time.
3rd November » With the encouragement of the United States, Panama Separation of Panama from Colombia known as separates from Colombia.
17th November » The Russian Social Democratic Labour Party splits into two groups: the Bolsheviks (Russian language or Russian for "majority") and Mensheviks (Russian for "minority").
18th November » The Hay–Bunau-Varilla Treaty is signed by the United States and Panama, giving the United States exclusive rights over the Panama Canal Zone.
14th December » The Wright brothers make their first attempt to fly with the 'Wright Flyer' at Kitty Hawk, North Carolina.
17th December » The Wright brothers make the first controlled powered, heavier-than-air flight in the 'Wright Flyer' at Kitty Hawk, North Carolina.
30th December » Iroquois Theatre fire named A fire at the Iroquois Theater in Chicago called Chicago, Illinois kills at least 605.