A hydroelectric plant at the Saint Croix Falls Dam supplies power to the Minneapolis–Saint Paul metropolitan area.

The presence of older glacial deposits within the St. Croix River basin proves that the Laurentide Ice Sheet has repeatedly glaciated this region during the Pleistocene Epoch.

Within this region these older deposits consist of gray calcareous tills associated with glaciofluvial yellowish-brown sand and gravel and glacial lacustrine silts and clays of the Pierce Formation and overlying reddish-brown tills and associated sand and gravel of the River Falls Formation.

These earlier deposits occur as erosional remnants either capping hills or buried by the latest advance of the Laurentide Ice Sheet over this area during the Last Glacial Maximum.

[9] Light and noise pollution are concerns of those opposed to the bridge, who cites the original act that kept such activity to the south along the Interstate 94 corridor.

Its mission is to inspire stewardship to forever ensure the rare ecological integrity of the St. Croix and Namekagon Riverway.

The upper portion of the river—originally called the north branch of the St. Croix River—was known to the Ojibwa as Manoominikeshiinh-ziibi (Ricing-Rail River).

However, by 1843, Joseph Nicollet's Hydrographical Basin of the Upper Mississippi River reinforced the name provided by Franquelin's 1688 map.

About 500 million years ago, a shallow sea covered the area, laying down layers of sand and minerals that make up much of the sandstone bluffs now seen along the river.

At the time of European arrival in the region, the river valley and the surrounding area was occupied by the semi-nomadic Ojibwe, Dakota and nine other American Indian tribes.

[19] After the end of the French and Indian War in 1763, British traders entered the area and grew in numbers and influence with the help of the powerful North West Company.

[12]: 32–35 The 1837 Treaty of St. Peters with the Ojibwe was signed at St. Peters (now Mendota) which ceded to the United States government a vast tract of land in what today is north central Wisconsin and central Minnesota, roughly bounded by the Prairie du Chien Line in the south, Mississippi River in the west, St. Croix and Chippewa River watersheds in the north, and a 25-mile parallel east of the Wisconsin River in the east.

During this time the population of Stillwater boomed, several additional sawmills were opened, and the town saw an influx of capital, primarily from lumber companies based downriver in St. Louis, Missouri.

In 1856 construction began on a booming site two miles north of Stillwater, which was used to store and sort the lumber floating downstream and remained in operation for over fifty years.

[12]: 102  The St. Croix Boom Site is now a wayside rest and National Historic Landmark along Minnesota State Highway 95.

[19] The lumber industry continued to grow throughout the latter half of the 19th century, with progressively larger spring drives and consequent dangers to navigation on the river above Stillwater.

[19] The lumber industry continued until the last major log drive in 1912 marked the end of the rich white pine forests of the area.