* 1803: Ohio admitted into the Union with an enabling act authorizing the inhabitants to set up a state government.

A request, dated January 13, 1812, by William Clark ( famous for his exploration of the American West with Meriwether Lewis and the Corps of Discovery from 1803 to 1805 ), then the governor of the Louisiana Territory ( the territory was renamed the Missouri Territory soon after the quake to eliminate confusion with the new state of Louisiana ), asked for federal relief for the " inhabitants of New Madrid County.

By the beginning of the 19th century the population had reached 3000 inhabitants, but a famine in 1803 and a smallpox epidemic the following year reduced the population again.

It was founded in 1803 as Christ's Church by the Protestant inhabitants of New Orleans, and is today the official seat of the Bishop of Louisiana, in the Episcopal Diocese of Louisiana.

The Americans thought that Napoleon might withdraw the offer at any time, preventing the United States from acquiring New Orleans, so they agreed and signed the Louisiana Purchase Treaty on April 30, 1803.

On Saturday, April 30, 1803, the Louisiana Purchase Treaty was signed by Robert Livingston, James Monroe, and Barbé Marbois in Paris.

The presidential authority to commission officers would have a large impact on the 1803 case Marbury v. Madison, where outgoing Federalist President John Adams feverishly signed many commissions to the judiciary on his final day in office, hoping to, as incoming Democratic-Republican President Thomas Jefferson put it, " into the judiciary as a stronghold.

It was created by an Act of the Legislature in 1803 after the Wilkinson Treaty was signed with the Creek Indians on January 16, 1802, which ceded part of the Tallassee Country and part of the lands within the forks of the Oconee and Ocmulgee Rivers to the United States.

The Enclosure of the Parish of Wraysbury was ordered by a private Enclosure Act of 1799 and was signed by the commissioners in 1803.

In the Second Anglo-Maratha War ( 1803 – 1805 ), the Peshwa Baji Rao II signed a similar treaty.

* The Louisiana Purchase, which brought Arkansas into the U. S., was signed in 1803.

After the occupation of Hanover by Napoleonic troops the Convention of Artlenburg, also called the Convention of the Elbe, was signed on 5 July 1803 and formally dissolved the Electorate of Hanover.

On 17 December 1803, Raghoji II Bhonsle of Nagpur signed the Treaty of Deogaon in Orissa with the British after the Battle of Laswari and gave up the province of Cuttack ( which included Mughalbandi / the coastal part of Orissa, Garjat / the princely states of Orissa, Balasore Port, parts of Midnapore district of West Bengal ).

On 30 December 1803, the Daulat Scindia signed the Treaty of Surji-Anjangaon with the British after the Battle of Assaye and Battle of Argaon and ceded to the British Rohtak, Gurgaon, Ganges-Jumna Doab, the Delhi-Agra region, parts of Bundelkhand, Broach, some districts of Gujarat, fort of Ahmmadnagar.

On 17 December 1803, Raghuji Bhonsale ( II ) of Nagpur signed the Treaty of Deogaon with the British after the Battle of Laswari and gave up the province of Cuttack including Balasore.

Napoleon Bonaparte signed the Act of Mediation on 19 February 1803 and, in the process, the canton of Baden was dissolved and united with the cantons of Aargau and Fricktal.

Following the Act of Mediation, signed by Napoléon Bonaparte on March 19, 1803, Brugg was definitively made a district capital in the newly arranged Canton of Aargau.

On June 7, 1803, Buckongahelas signed the Treaty of Fort Wayne in Indiana ; the US set new boundaries for the Lenape and other nations.

The value of the Caucasian mineral waters led to the construction of a resort in 1803, and the first studies of their medical properties began thereafter: on April 24, Alexander I signed a decree which made the mineral waters state property.

A treaty of friendship and commerce with the Republic of San Marino was signed on June 10, 1802, the Concordat with the Holy See on September 16, 1803.

Their signed protest was dated September 10, 1803.

In 1763 the last Este Duke of Modena Ercole III ( who did not die until 1803 ) signed a treaty with the Empress Maria Theresa engaging the nine-year old Ferdinand to his only daughter Maria Beatrice, making him thus his heir.

On February 19, 1803, President Jefferson signed the act of Congress that approved Ohio's boundaries and constitution.

On April 30, 1803, the two nations signed a treaty confirming the Louisiana Purchase.

In 1803, the King of Spain, Carlos IV, made a petition to the Catholic Church, to have Arizmendi named Bishop.

He chose property in Elgin County in adjoining townships, Dunwich and Aldborough, when his petition for was granted in 1803.

He was Member of Parliament ( MP ) for Great Grimsby from 1803 until his re-election in 1807 was overturned on petition in 1808, and for Lincolnshire from 1807 to 1823.

Its early growth owed much to the work of the Duc de Richelieu, who served as the city's governor between 1803 and 1814.

In 1803, Irkutsk became a center of Siberian general-governor unit, and in 1822 it became a center of Eastern Siberian general – governor unit.

In 1803 an act of the Georgia legislature called for the establishment and survey of a town to be named in honor of the current governor, John Milledge.

* William Allen ( 1803 – 1879 ), born in Edenton, was later governor of Ohio

He named this village " Tiffin " in honor of Edward Tiffin, first governor of Ohio and later member of the United States Senate, and a man who had fought to finally win statehood for the Ohio Territory in 1803.

* James Douglas ( governor ) ( 1803 – 1877 ), Scottish-Canadian governor of the colony of Vancouver Island

Arthur St. Clair was the territory's governor until November 1802, when President Thomas Jefferson removed him from office and appointed Charles Willing Byrd, who served the position until Ohio became a state and elected its first governor, Edward Tiffin, on March 3, 1803.

* Sir James Douglas ( governor ) ( 1803 – 1877 ), governor of Vancouver Island and British Columbia ; head of Hudson's Bay Company operations in the Columbia District

* William Allen ( governor ) ( 1803 – 1879 ), American politician from Ohio

William C. C. Claiborne ( 1775 – 1817 ), a lawyer and former Democratic-Republican Congressman from Tennessee ( 1797 – 1801 ), was governor and superintendent of Indian affairs in the Mississippi Territory from 1801 through 1803.

Sevier served six two-year terms as Tennessee's governor, from 1796 until 1801, and from 1803 to 1809, with term limits preventing a fourth consecutive term in both instances.

When Sevier announced his candidacy for governor in 1803, Roane and Jackson made documents from the Nashville land office scandal public, and accused Sevier of bribery.

Claiborne was appointed governor and superintendent of Indian affairs in the Mississippi Territory from 1801 through 1803.

* William Hornby ( governor ) ( c. 1723 – 1803 ), Governor of Bombay

* Sir George Bonham, 1st Baronet ( 1803 – 1863 ), British colonial governor and governor of Hong Kong

In 1803, he received a full pardon from the colony's governor, King.

* John Catlin ( 1803 – 1874 ), acting governor of the Wisconsin Territory

Sir Samuel George Bonham, 1st Baronet KCB ( Chinese Translated Name 文咸 or 般咸 ) ( 7 September 1803 – 8 October 1863 ) was a British colonial governor, who became the 3rd Governor of Hong Kong.

Sir James Douglas KCB ( August 15, 1803 – August 2, 1877 ) was a company fur-trader and a British colonial governor on Vancouver Island in northwestern North America, particularly in what is now British Columbia.