The foundation of Baton Rouge, Louisiana, dates to 1721, at the site of a bâton rouge or "red stick" Muscogee boundary marker. It became the state capital of Louisiana in 1849.

Prehistory

Human habitation in the Baton Rouge area has been dated to about 8000 BC based on evidence found along the Mississippi, Comite, and Amite rivers. Earthwork mounds were built by hunter-gatherer societies in the Middle Archaic period, from roughly the 4th millennium BC.Rebecca Saunders, "The Case for Archaic Period Mounds in Southeastern Louisiana", Southeastern Archaeology, Vol. 13, No. 2, Winter 1994, accessed November 4, 2011 Proto-Muskogean divided into its daughter languages by about 1000 BC; a cultural boundary between either side of Mobile Bay and the Black Warrior River begins to appear between about 1200 BC and 500 BC, the Middle "Gulf Formational Stage". Eastern Muskogean began to diversify internally in the first half of the 1st millennium AD.Nicholas A. Hopkins, The Native Languages of the Southeastern United States (2007), with older literature. The early Muskogean nations were the bearers of the Mississippian culture which formed around AD 800. By the time the Spanish made their first forays inland from the shores of the Gulf of Mexico in the early 16th century, many political centers of the Mississippians were already in decline, or abandoned, the region at the time presenting as a collection of moderately-sized native chiefdoms interspersed with autonomous villages and tribal groups.

Colonial period

1699–1763: French period

French explorer Sieur d'Iberville led an exploration party up the Mississippi River in 1699. The explorers saw a red pole marking the boundary between the Houma and Bayagoula tribal hunting grounds. The French name le bâton rouge ("the red pole") is the translation of a native term rendered as Istrouma, possibly a corruption of the Choctaw iti humma "red pole";Rose Meyers, A History of Baton Rouge 1699-1812 (1976), 4 ff. André-Joseph Pénicaut, a carpenter traveling with d'Iberville, published the first full-length account of the expedition in 1723. According to Pénicaut,

From there [Manchacq] we went five leagues higher and found very high banks called écorts in that region, and in savage called Istrouma which means red stick [bâton rouge], as at this place there is a post painted red that the savages have sunk there to mark the land line between the two nations, namely: the land of the Bayagoulas which they were leaving and the land of another nation—thirty leagues upstream from the baton rouge—named the Oumas.

See also Red Sticks for the ceremonial use of red sticks among the Muscogee. The location of the red pole was presumably at Scott's Bluff, on what is now the campus of Southern University.Irene Stocksieker Di Maio (ed.), Gerstäcker's Louisiana: Fiction and Travel Sketches from Antebellum Times Through Reconstruction, LSU Press (2006) p. 307. It was reportedly a thirty-foot-high painted pole adorned with fish bones.Andrew C. Albrecht, "The Origin and Early Settlement of Baton Rouge, Louisiana," Louisiana Historical Quarterly 28.1 (1945), 5-68. The settlement of Baton Rouge by Europeans began in 1721 when a military post was established by French colonists.

1763–1779: British period

On February 10, 1763, the Treaty of Paris was signed following France's defeat by Great Britain in the French and Indian War. France ceded its territory in North America to Britain and Spain; Britain gained all French lands east of the Mississippi, except New Orleans.

During the Great Expulsion concurrent with the French and Indian War, the North American front of the French and Indian War, British colonial officers expelled about 11,000 Acadians from Acadia from eastern Canada. Many were transported to France and subsequently resettled in southern Louisiana (New Spain); they settled in an area west and south of Baton Rouge that would come to be known as Acadiana. The first group of Acadian settlers arrived in 1765, with Joseph Broussard. (At this point the Mississippi River was the dividing line between the newly-Spanish jurisdiction on the west, including Acadiana, and the newly-British West Florida, including Baton Rouge, on the east side.)

Eventually the settlers began calling themselves Cajuns, a name derived from Acadians (French: Acadiens.) They maintained a separate culture from that of later Anglo-American Southern Baptist settlers, continuing their traditions of distinct clothing, music, food, and Catholic faith. Today their descendants are part of the rich cultural “gumbo” of the Baton Rouge area.

Baton Rouge, now part of the newly established British province of West Florida, suddenly had strategic significance as the southwesternmost corner of British North America. Spain for a period had rule of New Orleans and all of the former French lands on the west side of the Mississippi River. They administered numerous historically-French colonial towns, such as St. Louis and Ste. Genevieve in present-day Missouri.

Baton Rouge slowly developed as a town under British rule. The authorities, headquartered in Pensacola, awarded land grants and were successful in attracting European-American settlers. When the older British colonies on the Atlantic coast of North America rebelled, beginning in 1775, the newer colony of West Florida — lacking a history of local government and distrustful of the potentially hostile Spanish nearby — remained loyal to the British Crown.

In 1778 during the American Revolutionary War, France declared war on Britain, and in 1779 Spain followed suit. That year, the Spanish Governor Don Bernardo de Gálvez led a militia of nearly 1,400 soldiers and a small contingent of rebellious English-speaking colonials from New Orleans toward Baton Rouge. They were victorious in the Battle of Fort Bute and the naval Battle of Lake Pontchartrain, before capturing the recently constructed Fort New Richmond in the Battle of Baton Rouge. Spanish officials renamed the site Fort San Carlos and took control of Baton Rouge.

At the conclusion of the Revolutionary War, Great Britain turned West Florida over to Spain.

1779–1810: Spanish period

A colony of Pennsylvania German farmers migrated north from Bayou Manchac, after a series of floods in the 1780s, and settled to the south of Baton Rouge. Known locally as "Dutch Highlanders" ("Dutch" being a corruption of Deutsch, in reference to their language), they settled along a line of bluffs that served as barrier to the Mississippi River floodplain.

Historic Highland Road, located in the heart of present-day Baton Rouge, was originally established as a supply road for the indigo and cotton plantations of the early settlers. The ethnic Germans named two major roads in the area, Essen and Siegen lanes, after cities in Germany. The Kleinpeter and Staring families were among the most prominent of the early German families in the area. Their descendants have remained active in local business affairs since.

In 1800, the Tessier-Lafayette buildings were built on what is now Lafayette Street and survive today. Development of sections followed. In 1805, the Spanish administrator, the Francophone creole Don Carlos Louis Boucher de Grand Pré, commissioned a plan for the area today known as Spanish Town. In 1806, Elias Beauregard led a planning commission for what is today known as Beauregard Town.

Statehood to Civil War

1810–1812: Republic of West Florida & Orleans Territory

As a result of the United States' 1803 Louisiana Purchase, it gained the former French territory in North America (retroceded by Spain to France). At that point, Spanish West Florida was almost entirely surrounded by the United States and its possessions. The Spanish fort at Baton Rouge became the only non-U.S. military post on the Mississippi River.

Several of the inhabitants of the Baton Rouge District began to organize conventions to plan a rebellion, among them Fulwar Skipwith, a Baton Rouge citizen. At least one meeting was held in a house on a street which has since been renamed Convention Street, in their honor. On September 23, 1810, the rebels overcame the Spanish garrison at Fort San Carlos; they unfurled the flag of the new Republic of West Florida, known as the Bonnie Blue Flag. The West Florida Republic existed for almost ninety (90) days, during which St. Francisville in present-day West Feliciana Parish served as its capital.

Seizing the opportunity, President James Madison ordered W. C. C. Claiborne to move in and seize the fledgling republic to annex into the Territory of Orleans. Madison used the premise that the territory had been a part of the U.S. since 1803, citing the terms of the Louisiana Purchase, an explanation largely believed to be a deliberate error. The rebels provided no resistance to Claiborne's forces. With minor resentment, they watched the "Stars and Stripes" raised on December 10, 1810. For the first time, nearly all of the land that would become the state of Louisiana lay within U.S. territorial borders.

1812–1860: Early statehood & incorporation as capital

In 1812, Louisiana was admitted to the Union as a state, and in 1817 Baton Rouge was incorporated. As the town was a strategic military post, between 1819 and 1822 the U.S. Army built the Pentagon Barracks, which became a major command post through the Mexican–American War (1846–1848). Lieutenant Colonel Zachary Taylor supervised construction of the Pentagon Barracks and served as its commander. In the 1830s, what is known today as the "Old Arsenal" was built. The unique structure originally served as a gunpowder magazine for the U.S. Army post.

In 1825, Baton Rouge was visited by the Marquis de Lafayette, French hero of the American Revolution, as part of his triumphal tour of the United States. The town feted him as the guest of honor at a banquet and ball. To celebrate the occasion and honor him, the city changed the name of Second Street to Lafayette Street.

In 1849, the Louisiana state legislature in New Orleans, dominated in number by wealthy rural planters, decided to move the seat of government to Baton Rouge. The majority of representatives feared a concentration of power in the state's largest city and the continuing strong influence of French Creoles in politics. In 1840, New Orleans' population was slightly over 102,000, then the third-largest city in the United States. Its thriving economy was largely sustained by the by-products of the domestic slave trade in addition to shipping; the city itself was the largest slave market in the nation. Products from the center of the country flowed through New Orleans for export, and ships arrived with a range of goods for the city and for towns and cities upriver. The 1840 population of Baton Rouge, on the other hand, was only 2,269.

New York architect James H. Dakin was hired to design the new capitol in Baton Rouge. Rather than mimic the federal Capitol Building in Washington, D.C., as so many other capitol designers had done, he conceived a neo-Gothic medieval castle, complete with turrets and crenellations, overlooking the Mississippi. In 1859, the Capitol was featured and favorably described in DeBow's Review, the most prestigious periodical in the antebellum South.Steuckrath, Prof. George."Historical Collections of Louisiana—Baton Rouge." Debow's review, Agricultural, commercial, industrial progress and resources. New Orleans (etc.): J.D.B. DeBow, (April, 1859) pp. 439-444 from Making of America Journal Articles, Library, University of Michigan But the riverboat pilot and writer Mark Twain loathed the sight; later in his Life on the Mississippi (1874), he wrote, "It is pathetic ... that a whitewashed castle, with turrets and things ... should ever have been built in this otherwise honorable place."Life on the Mississippi, New York: Houghton and Company, 1874, Chap. 40, pp. 416-17, digital version on Documents of the American South, University of North Carolina at Chapel Hill