Though modern Minnesota was born at Fort Snelling, down where the Minnesota River joins the Mississippi, it grew up along the St. Croix. The Dakota occupied the valley when French explorer Daniel Greysolon, Sieur du Lhut—the man presumed to be the first European to visit—passed through in 1680.

Swarms of fur traders, first the French and then later the English and Americans, weren’t far behind. Though some trading posts were built, there could be no settlement until the Ojibwe, who had taken over the valley by force from the Dakota, relinquished their lands in 1837.

The fur trade had largely gone bust by this time, though the river would soon transport another precious cargo. Lumberjacks moved in almost immediately after the treaty was signed, sending their logs downstream to the state’s first sawmill in Marine on St. Croix and later to Stillwater, which quickly grew into the river’s dominant lumbering center and one of the state’s ranking cities.

Many of the earliest settlers in the valley were wealthy New Englanders, and several of the towns they built still bear a resemblance to their original homes. Wisconsin became the 30th state in 1848, leaving the St. Croix Valley, which had been a part of the previous Wisconsin Territory, in a political vacuum.

A group of influential, though self-appointed, civic leaders hastily convened an August summit in Stillwater and elected American Fur Company director Henry Sibley to represent them in Congress. Though technically he had no right to a seat in Congress, and legally there wasn’t even a white population large enough to form a territory, Sibley and his allies put the Minnesota Territorial Act on President Zachary Taylor’s desk the next year.

The mills were largely silent and the logging camps empty by around 1915, but immigrant farmers tried to make a living off the land. The soil was far too sandy, however, and those who managed to get by struggled; others faced reality and gave up. As part of the relief effort during the Great Depression, the government bought out many of the farmers and reforested the land, leaving extensive state forests and parks along the river.

In 1968 the St. Croix was one of the eight original rivers added to the National Wild and Scenic Rivers System, initiating a second period of preservation by both the National Park Service and the states of Minnesota and Wisconsin.