Interstate State Park

Croix River borders the park and supports numerous fish and mussel species.HistoryIn the late 1800s, the threat of mining prompted citizens from Minnesota and Wisconsin to preserve the Dalles of the St. Croix River. Working together, the first interstate (Minnesota and Wisconsin) park in the nation was established. The Minnesota Legislature established this side of the park in 1895 and the Wisconsin Legislature followed in 1900. Today, the Minnesota and Wisconsin state parks operate separately and offer trails and scenic views along the St. Croix River.GeologyAbout 1.1 billion years ago, earthquakes erupted from Taylors Falls to Lake Superior and caused at least 10 different lava flows. The hardened basalt rock from these lava flows partly formed the Dalles of the St. Croix and the bottom of the river. From 530 million years ago up until 70 million years ago, the state was washed by advancing and retreating seas. Evidence of these ancient seas is revealed in the sedimentary rocks and formations found in the park. These rocks contain fossil remains of ancient animals, evidence of various creatures, and ripple marks left in stone by the now vanished seas.There have been many different St. Croix Valleys through the ages. The first formed about 70 million years ago and current valley formed about 10,000 years ago. A glacier formed both Glacial Lake Duluth, now Lake Superior, and Glacial Lake Grantsburg, now extinct. Glacial Lake Duluth was much larger than modern day Lake Superior. As this giant body of ice thawed, its meltwaters roared south to carve out the broad valley of the St. Croix. Only very resistant basalts were able to partially withstand the torrent, resulted in the dalles, potholes, and cliffs we see today.LandscapeThe park's diverse landscape includes floodplains and maple, oak and pine forests. Though small in size, the park is a haven for rare and endangered species.