Father Jacques Marquette S.J. (June 1, 1637 – May 18, 1675), sometimes known as Père Marquette or James Marquette, was a French Jesuit missionary who founded Michigan's first European settlement, Sault Ste. Marie, and later founded St. Ignace, Michigan. In 1673 Father Marquette and Louis Jolliet were the first Europeans to see and map the northern portion of the Mississippi River.

Jacques Marquette was born in Laon, France, on June 1, 1637 and joined the Society of Jesus at age seventeen. After he worked and taught in France for several years, the Jesuits assigned him to Quebec in 1666 as a missionary to the Indigenous peoples of the Americas. He showed great proficiency in learning the local languages, especially Huron. In 1668 Father Marquette (French: Père Marquette) was moved by his superiors to missions farther up the St. Lawrence River in the western Great Lakes region. He helped found missions at Sault Ste. Marie in present-day Michigan and at La Pointe, on Lake Superior near the present-day city of Ashland, Wisconsin. At La Pointe he encountered members of the Illinois tribes, who told him about the important trading route of the Mississippi River. They invited him to teach their people, whose settlements were mostly further south. Because of wars between the Hurons at La Pointe and the neighboring Lakota people, Father Marquette left the mission and went to the Straits of Mackinac; he informed his superiors about the rumored river and requested permission to explore it.

Louis Jolliet (September 21, 1645 – last seen May 1700), also known as Louis Joliet, was a Canadian explorer known for his discoveries in North America. Jolliet and Jesuit Father Jacques Marquette, a Catholic priest and missionary, were the first Europeans to explore and map much of the Mississippi River in 1673.

Jolliet was born in 1645 in a French settlement near Quebec City. When he was seven years old, his father died and his mother remarried a successful merchant. Jolliet's stepfather owned land on the Ile d'Orleans, an island in the Saint Lawrence River in Quebec that was home to First Nations. Jolliet spent much time on Ile d'Orleans, so it was likely that he began speaking Aboriginal languages at a young age. During his childhood, Quebec was the center of the French fur trade. The Natives were part of day-to-day life in Quebec, and Jolliet grew up knowing a lot about them.

Jolliet attended a Jesuit school in Quebec and received minor orders in 1662, but abandoned his plans to become a priest in 1667. He spoke English, Spanish, and French.