Antoine LeClaire was born December 15, 1797 in St. Joseph, Michigan, of a French-Canadian father and a Native-American Pottawottomie mother. His father owned several trading posts, and Antoine grew up speaking at least a dozen Native American dialects, as well as French, Spanish (his stepmother was from Spain) and a very little English. Following in his father's footsteps, Antoine is said to have established his own trading post in Milwaukee, Wisconsin at the age of twelve, and began to trade extensively with several Native American tribes.
Most of the local tribes favored the British over the relatively new, and expanding, American nation, an opinion that was fueled by propaganda and promises from the few remaining British forts in the territories. Despite this, the teenaged Antoine actively fought on the side of the Americans in the War of 1812. He was captured by the British in Peoria, Illinois and taken to a camp in Alton until the end of the war. There he met General William Clark, who was much impressed with Antoine's linguistic abilities. General Clark sent Antoine to school to learn how to speak proper English, and recruited him into Government service as an interpreter. In 1818, Antoine was sent to Fort Armstrong, on the Mississippi River Island now known as Arsenal Island. There, he met George Davenport, with whom he enjoyed a lifelong friendship.
In 1820, Antoine married Marguerite LaPage (b. 1802), the granddaughter of Acoqua, a Sac chief.
Antoine and Marguerite spent the next several years studying the movements of Native Americans in Arkansas. The couple returned to Fort Armstrong in 1827, where Antoine acted as interpreter for several important treaties between the United States and Native American tribes.
Antoine LeClaire was present at the Black Hawk treaty in 1832, during which the United States purchased the Sac and Fox territories West of the Mississippi. Because of an outbreak of cholera at Fort Armstrong, the treaty was signed on the Iowa shore. During the proceedings, Keokuk, the Sac chief, donated a reserve of land to Antoine's wife, with the condition that Antoine build his home on the exact spot where General Scott signed the treaty. The Sacs and Fox then gave Antoine the land where the town of LeClaire now stands, and the Pottawottomies gave him land on the Illinois side of the river, where the city of Moline stands today. In the spring of 1833, after Congress ratified the Black Hawk Treaty, Antoine began building a small log house on the site of the treaty. This was replaced later by a small white house called "The Treaty House."
Though Antoine owned vast tracts of land, he did not have the money or the connections to encourage area development; it has also been suggested that Antoine might have felt his French Canadian-Native American ancestry to be a liability in attracting settlers. In 1832, Antoine and several other men, most having English ancestry and surnames, including Colonel George Davenport, planned a town to be built on the Iowa side of the Mississippi across from Ft. Armstrong. Antoine was paid $1,750 for the initial site, retaining a one-eight interest.
Although the new town was named after George Davenport, possibly at Antoine's suggestion, Antoine is considered by many to be its principle founder. His generosity built much of the town, including several churches of assorted denominations and many public buildings. His donations of land helped Davenport win the position of county seat over Rockingham. He owned the first foundry and hotel in the town, and in 1833, he was appointed the first postmaster of Davenport, and also the first Justice of the Peace. In 1834, he established the first ferry service between Davenport and the town of Stephenson, Illinois (the present day city of Rock Island). Antoine, now a successful businessman, retired from government employment; his last work as an interpreter was at the 1842 signing that opened up the rest of the Iowa Territory for settlement.
Antoine and Marguerite never had children of their own, but informally adopted Louis Antoine LeClaire (1842), son of Antoine's half brother, Alexis LeClaire, after Alexis' death in 1849. Antoine and his nephew apparently enjoyed a close father-son relationship; according to Louis, when Millard Fillmore visited Davenport around 1853, Antoine introduced Louis to the former president by saying, "Mr. President, I want you to meet my boy."
The LeClaires lived in the Treaty House until 1855, when they moved to a mansion at the present-day address of 630 East 7th Street, in the middle of the "LeClaire Reserve." Antoine offered the Treaty House to the Mississippi and Missouri Railroad, which used the little house as the town's first depot. In the 1880s, the mansion, called the LeClaire House, became the residence for the first Bishop of the new Davenport Catholic Diocese. By World War I, the mansion had degenerated into a boarding house, but in 1976, the Davenport Bicentennial Commission bought the LeClaire House and is restoring it as a community showpiece.
Antoine was known for both his generosity and his honesty. In 1857, an economic panic spread through the Midwest, and many banks failed, as frightened people began withdrawing all their money. In Davenport, the Cook and Sargent Bank looked as though it, too, was in danger. Antoine advised the citizens of Davenport to be calm and to keep their money in the bank. He gave his word that if anyone lost money through Cook and Sargent, he would pay them back out of his own pocket. So many people believed in Antoine that the panic ground to an immediate halt. Soon after, however, the bank failed for other reasons, and though Antoine expressed fear that even his large fortune would not be enough to carry out his promise, he managed to refund every single banknote. It is suspected that the strain hastened his death.
Antoine LeClaire died on September 25, 1861 and was buried on the grounds of St. Marguerite's Church, a church he had donated land and money to build. Marguerite LeClaire died on October 18, 1876, and was buried next to her husband. In 1889, the Catholic Diocese chose St. Marguerite's as the perfect site for the planned Sacred Heart Cathedral, popularly called Cork Hill Cathedral. Antoine and Marguerite were moved to St. Marguerite's Cemetery, now named Mount Calvary. Though Louis inherited what was left of the estate, all the citizens of Davenport can be said to be the heirs of the generosity and affection of Antoine LeClaire.