6/21/2026
Our visit to Interstate State Park in Wisconsin proved that potholes are not limited to highways! Some of the park’s most interesting features are its famous glacial potholes—deep, rounded holes carved into solid rock thousands of years ago by swirling water, sand, and stones. Apparently, nature had perfected pothole construction long before road departments got involved!
The park sits along the beautiful St. Croix River, directly across from another Interstate State Park on the Minnesota side. The Wisconsin park, established in 1900, is the oldest state park in Wisconsin. The river flows through the steep, rocky gorge known as the Dalles of the St. Croix, creating a dramatic landscape of cliffs, unusual formations, and rushing water.
Surrounded by steep cliffs, rugged stone, and thick forest, the St. Croix River looked peaceful, yet powerful. It was easy to see how the tremendous flows of glacial meltwater had carved the deep gorges at the end of the Ice Age.
We began at the visitor center, where we watched an interesting and informative movie about the park’s geology and history. It helped to set the background for what we were about to see—and gave us just enough geological knowledge to sound reasonably intelligent as we examined the rocks later… “That’s a very deep hole,” vs “That’s a glacial pothole!”
We carefully made our way around the rocks, peering into potholes of different sizes and shapes while trying not to become permanent geological exhibits ourselves (yes, one of us fell today!). The terrain certainly required attention, but every few steps brought another unusual formation or a beautiful view of the river below.
Some holes were deep, smooth, and perfectly rounded. It was difficult to imagine that moving water and small rocks could slowly drill such impressive holes into solid bedrock. But glaciers had plenty of time on their hands!
We could walk right up to these “potholes”—some are small enough to step over, while others are large enough to stand in—these are considered some of the best examples in the world.
We thoroughly enjoyed our visit to Interstate State Park. Walking through the park became much more than simply enjoying a pretty trail. The visit turned out to be a wonderful combination of education, scenery, and enjoyable walking. The movie gave us the background, the trails brought the story to life, and the park left us with a new appreciation for Wisconsin’s remarkable geological history. Learning new things about a state we formerly lived in…a real bonus!
This sign designates the western terminus of the Ice Age National Scenic Trail.
This was a good place to see the glacier’s terminal moraine.
