How did Jacques Marquette and Louis Jolliet explore the Mississippi River in 1673?

In 1672, the governor of New France commissioned Louis Jolliet to explore the Mississippi River, and he was joined by the Jesuit missionary Jacques Marquette.12

On May 17, 1673, the expedition departed from Michilimackinac in two birchbark canoes. They traveled to Green Bay, ascended the Fox River, and crossed a portage to the Wisconsin River, entering the Mississippi on June 17.12

As they paddled downstream, the explorers paused to hunt, take notes, and gather information from local Indigenous peoples. They reached the mouth of the Arkansas River in July, where they concluded from their observations and interactions with the Quapaw people that the river flowed south into the Gulf of Mexico rather than the Pacific Ocean. Fearing potential conflict in Spanish-controlled territories, the party turned back, returning via the Illinois River. Their journey provided the first accurate data on the river's course, which was documented in Marquette’s surviving journal.12