Julien Dubuque (died March 24, 1810) was a French Canadian who arrived near what now is known as Dubuque, Iowa - which was named after him. He was one of the first white men to settle in the area. He initially received permission from the Fox Native American tribe to mine the lead in 1788. Subsequently the Spanish confirmed that by giving him a land grant in 1796.
Once he had received permission from the Fox to mine lead, Julien Dubuque remained in the area for the rest of his life. He befriended the local Mesquakie Chief Peosta - for whom the nearby town of Peosta, Iowa is named. It is widely believed that Dubuque married Peosta's daughter, who was supposedly named "Potosa"; however, there is no evidence that this was ever the case. Those who back the marriage claim point to letters that mention a Madame Dubuque as meaning Dubuque's wife.
The name "Potosa" often appears in fanciful origin stories for the name Potosi, a small Wisconsin town located north of Dubuque, Iowa, which was founded in the 1830s as a lead-mining settlement.
When what would eventually become Iowa was opened up to European settlement, the settlement in the area where he had mined was named after him. It was known by several names, including DuBuque's Mines. Eventually, the village became the first city in Iowa, and was named Dubuque in memory of Julien Dubuque. Dubuque's resting place and memorial lie on a cliff facing the Mississippi river at the Julien Dubuque Monument in the Mines of Spain State Recreation Area and E. B. Lyons Nature Center.