On April 6, the Church of Jesus Christ of Latter-Day Saints is founded by Joseph Smith Jr. (1805-1844), in Fayette, New York. In Palmyra, New York, The Book of Mormon is published for the first time; Smith has translated it, he says, from golden tablets he found buried near Palmyra.

The first wagon trains to cross the Rocky Mountains arrived in California.

The U.S. Congress passes the Indian Removal Act.

The world's population tops 1,000,000,000 (it had been roughly 750 million only 50 years earlier).

Nat Turner leads a slave rebellion in Southampton, Virginia, killing at least 57 whites. Hundreds of black slaves are killed in retaliation.

Alabama makes it illegal for enslaved or free blacks to preach.

In Boston, William Lloyd Garrison founds the abolitionist newspaper, The Liberator, signaling a dramatic shift in the antislavery movement. In the previous decades, it had centered in the South and favored a combination of compensated emancipation and colonization of freed slaves back to Africa. In the 1830s, the abolitionist movement becomes the dominant voice among antislavery advocates. Abolitionists demand the immediate end to slavery, which they consider to be a moral evil, without compensation to slaveowners.

Nat Turner, a literate slave who believes he is chosen to be the Moses of his people, instigates a slave revolt in Virginia. He and his followers kill 57 whites, but the revolt is unsuccessful and up to 200 slaves are killed. After an intense debate, the Virginia legislature narrowly rejects a bill to emancipate Virginia's slaves. The widespread fear of slave revolts, compounded by the rise of abolitionism, leads legislatures across the South to increase the harshness of their slave codes. Also, expressions of anti-slavery sentiment are suppressed throughout the South through state and private censorship.

North Carolina enacts a statute that bans teaching enslaved people to read and write.

Slave Revolt: Virginia Slave preacher Nat Turner leads a two-day uprising against whites, killing about 60. Militiamen crush the revolt then spend two months searching for Turner, who is eventually caught and hanged. Enraged Southerners impose harsher restrictions on their slaves.

Oberlin College is founded in Ohio. It admits African-Americans. By 1860, one third of its students are black.

In November, the New York and Harlem Railroad begins service, and heralds the start of rapid mass transit in New York City. Two horse-drawn rail cars operate every 15 minutes between 14th Street and Prince Street, along the Bowery. The fare is 25 cents.

Electric telegraph invented by Samuel Morse.

The American Anti-Slavery Society is established in Philadelphia.

The British Parliament abolishes slavery in the entire British Empire.

Ada Lovelace Meets Charles Babbage

South Carolina bans the teaching of blacks, and slave or free, in its borders.

Hércules Florence, a French-Brazilian painter and the isolate inventor of photography in Brazil, coined the word photographie for his technique, at least four years before John Herschel coined the English word photography.

Charles Babbage invents the "analytical engine" — the forerunner of the modern computer.

Federal troops are ordered to put down a riot by workers along the Chesapeake and Ohio Canal. It is the first time federal troops have been used to settle a labor battle in the United States.

Texas declares its independence from Mexico. In its constitution as an independent nation, Texas recognizes slavery and makes it difficult for free blacks to remain there.

Southern states expel abolitionists and forbid the mailing of antislavery propaganda.

Henry Fox Talbot produces durable silver chloride camera negatives on paper and conceives the two-step negative-positive procedure used in most non-electronic photography up to the present.

The first volume of La Dèmocracie en Amèrique (Democracy in America), by Alexis de Tocqueville (1805-1859), is published in France. Tocqueville, a historian and politician and member of the French aristocracy, writes about the American people and their institutions, based on his 9 months of travels through the United States and eastern Canada in 1831-1832.

The US flag is modified to have twenty-five stars, reflecting the addition of one new state: Arkansas.

Alonzo D. Phillips, a shoemaker from Springfield, Massachusetts, patents the phosphorous match.

Davy Crockett killed, as Texans are defeated by the Mexican army at the Alamo.

In Paris, the Arc de Triomphe is completed. The arch was ordered built by Napoleon in 1806.

Texas gains independence from Mexico after winning the battle of San Jacinto.

The US flag is modified to have twenty-six stars, reflecting the addition of one new state: Michigan.

Charles Babbage published a paper describing a mechanical computer that is now known as the Analytical Engine

Samuel F. B. Morse sends his first message by electric telegraph — "What hath God wrought!" — on an experimental line between Washington DC and Baltimore, Maryland.

Martin Van Buren becomes eighth president of the United States.

William IV, King of Great Britain, dies.

The S.S. Sirius and the S. S. Great Western are the first ships powered entirely by steam to cross the Atlantic. Both ships are designed by engineer Isambard Kingdom Brunel (1806-1859).

Coronation of Victoria as queen of Great Britain.

La Amistad was a 19th-century two-masted schooner, owned by a Spaniard living in Cuba. It became renowned in July 1839 for a slave revolt by Mende captives, who had been enslaved in Sierra Leone, and were being transported from Havana, Cuba to their purchasers' plantations. The African captives took control of the ship, killing some of the crew and ordering the survivors to sail the ship to Africa. The Spanish survivors secretly maneuvered the ship north, and La Amistad was captured off the coast of Long Island by the brig USS Washington. The Mende and La Amistad were interned in Connecticut while federal court proceedings were undertaken for their disposition. The owners of the ship and Spanish government claimed the slaves as property; but the US had banned the African trade and argued that the Mende were legally free. Because of issues of ownership and jurisdiction, the case gained international attention. Former president John Quincy Adams argued on behalf of the slaves when the appeal was brought before the U.S. Supreme Court, which eventually determined the Africans to be free men. The case became a symbol in the United States in the movement to abolish slavery.

Louis-Jacques-Mand Daguerre perfects and presents the daguerreotype process as the first publicly available photographic process (which for nearly twenty years was also the one most commonly used). To make the image, a daguerreotypist would polish a sheet of silver-plated copper to a mirror finish, treat it with fumes that made its surface light sensitive, expose it in a camera for as long as was judged to be necessary, which could be as little as a few seconds for brightly sunlit subjects or much longer with less intense lighting; make the resulting latent image on it visible by fuming it with mercury vapor; remove its sensitivity to light by liquid chemical treatment, rinse and dry it, then seal the easily marred result behind glass in a protective enclosure.

Henry Fox Talbot publicly introduces the paper-based process he worked out in 1835, calling it "photogenic drawing", but it requires much longer exposures than the daguerreotype and the results are not as clear and detailed.

John Herschel introduces hyposulfite of soda (now known as sodium thiosulfate but still nicknamed "hypo") as a highly effective fixer for all silver-based processes. He also makes the first glass negative.

Sarah Anne Bright creates a series of photograms, six of which are known to still exist. These are the earliest surviving photographic images created by a woman.

Although a bicycle consisting of a frame and wheels has existed for years, blacksmith Kirkpatrick MacMillan (1813-1878), introduces the first bicycle in its modern form, with brakes and pedals. The bike has iron tires and weighs nearly 60 pounds.

Inventor Erastus Brigham Bigelow (1814-1879) introduces the power loom in Massachusetts.

The first electric clock is built by physicist Carl August Steinheil (1801-1870).

In response to the British opium trade, Lin Zexu wrote a letter to Queen Victoria, urging her to end the opium trade: We find that your country is sixty or seventy thousand li from China. Yet there are barbarian ships that strive to come here for trade for the purpose of making a great profit. The wealth of China is used to profit the barbarians. That is to say, the great profit made by barbarians is all taken from the rightful share of China. By what right do they then in return use the poisonous drug to injure the Chinese people? Even though the barbarians may not necessarily intend to do us harm, yet in coveting profit to an extreme, they have no regard for injuring others. Let us ask, where is your conscience? The letter to the Queen never reached her. Belatedly, it was delivered and published in The Times of London.

Lin Zexu was a Chinese scholar-official of the Qing dynasty best known for his role in the First Opium War of 1839 42. In March 1839, Lin arrived in Guangdong Province to take measures that would eliminate the opium trade. He was a formidable bureaucrat known for his competence and high moral standards, with an imperial commission from the Daoguang Emperor to halt the illegal importation of opium by the British. Upon arrival, he made changes within a matter of months. He arrested more than 1,700 Chinese opium dealers and confiscated over 70,000 opium pipes. He initially attempted to get foreign companies to forfeit their opium stores in exchange for tea, but this ultimately failed. Lin resorted to using force in the western merchants' enclave. A month and a half later, the merchants gave up nearly 1.2 million kg (2.6 million pounds) of opium. Beginning 3 June 1839, 500 workers laboured for 23 days to destroy it, mixing the opium with lime and salt and throwing it into the sea outside of Humen Town. Lin composed an elegy apologising to the gods of the sea for polluting their realm.

The First Opium War between Britain and China occurs between 1839 and 1842, triggered when Chinese officials attempt to prevent the sale of narcotics (opium) to the Chinese people by the British East India trading Company. The British respond by bringing in gunboats and shelling Chinese coastal cities.

The process of vulcanization, developed by Charles Goodyear, makes possible the commercial use of rubber.