His first wife, as with many traders of the era, was a Native American woman, whose name no longer survives, only that she died giving birth to their daughter Marie.

After returning to Chicago and failing to convince commander Heald to stay in the fort, Kinzie ultimately enlisted fellow trader Alexander Robinson, who eventually managed to evacuate some survivors to Grand River and Detroit.

John Kinzie then traveled to St. Joseph, where he convinced several native American leaders to travel to Greenville, Ohio to attend an American peace conference which led to the Treaty of Greenville (1814), although other Native leaders (particularly Main Poc refused)[15] When the U.S. Army returned to rebuild Ft. Dearborn in 1816, Beaubien also returned to Chicago.

Beaubien purchased a house or cabin south of the Fort Dearborn ruins, which he transformed into a barn in 1817 after erecting a new residence and small trading post.

After the U.S. Government ended its factor system for trading with the Indians, Beaubien would acquire the former U.S. Factorhouse, originally a part of the second Fort Dearborn, from the American Fur Company in 1823 for $500.

Then, the animal decline, as well as an influx of white settlers into the ceded Potawatomi lands caused American Fur Company operations in the Chicago Region to end abruptly(around the time John Kinzie died of a stroke in January 1828).

[20] Meanwhile, the Sauk warrior Black Hawk gained support from remaining Potawatomis in northern Illinois and Wisconsin, including Billy Caldwell, displacing from power natives and metis whom Beaubien had long befriended, such as Alexander Robinson, Shabbona and Joseph La Framboise.

[21] John Kinzie's half-brother, Thomas Forsyth, who had been the Indian agent for the Sauk and Meskwaki peoples in Western Illinois (and lived in St. Louis) was rather abruptly dismissed as part of a shake-up within the Andrew Jackson administration, leading to an U.S. Army intelligence failure as tensions worsened.

[23] In 1835, during a real estate boom and after Robert A. Kinzie (the trader's son) had success claiming a different downtown tract, Beaubien seemingly purchased the site of Fort Dearborn (75.69 acres) through the local government land agent for $94.61, although his two previous attempts had received letters of rejection on the grounds that it was a military reservation.

[24][25] Unlike his purchase of the first carriage in town, or the second piano (for his daughters' use),[20] this led to litigation, specifically his downstate lawyer's attempt to evict the fort's commandant, Major Lafayette Wilcox.

[27] When Beaubien appealed, the Illinois Supreme Court (in an opinion drafted by his friend Theophilus W. Smith) found his claim valid on the grounds that the state legislature had never authorized the military reservation.

Following the decision, the U.S. District Court ordered Beaubien's payment returned, the military realized the fort unnecessary since Native Americans had left the area, and the General Land Office proceeded to ready to ready the property for subdivision and public auction as the "Fort Dearborn Addition to Chicago" (reserving only space for a lighthouse and quarters for the harbormaster).

Accounts differ as to whether he simply sold the lot he mad managed to purchase at the 1836 land sale, or was evicted from his remaining buildings in Chicago.

Some accounts indicate that Beaubien's farm from 1840 to 1850 was near that of his long-time metis friend and fellow trader Alexander Robinson, also on the Des Plaines river.

[35][36] A small Chicago street near the lakefront, "Beaubien Court" is named after the founder and gave access to the Illinois Central Railroad's freight warehouses.