This was a major barrier to Native Americans and early Europeans traveling by canoe, which they bypassed with the challenging Grand Portage of the St. Louis River.

The 9 miles (14 km) of the route between Carlton and Highway 23—which include the park—are designated the Rushing Rapids Parkway, a state scenic byway.

The CCC camp built a rustic swinging bridge over the St. Louis River just slightly downstream from some torrential rapids and waterfalls.

In 2012 the Duluth area experienced a record-setting rainstorm that resulted in flooding that filled the gorge with debris, devastated the park's roads and trails, and destroyed the historic Swinging Bridge that crosses the St. Louis River.

All the major landmarks in Jay Cooke are built with local basalt or gabbro stone and dark planks and logs.

According to an early report from the Pine Journal, at least one stone pillar and half of another were washed away, and the bridge decking was "twisted and mangled.

[7] Minnesota geography is dominated by three major watersheds which carry the surface waters of the state north to Hudson Bay, east to the Great Lakes, and south into the Mississippi River.

The rivers, creeks, and associated lakes within these drainage basins essentially describe the route geography of the thoroughfares used by American Indians for centuries, and later by European explorers, missionaries, and fur traders.

"[8] It was a rough trail of steep hills and swamps that began at the foot of the rapids above the present day Fond du Lac ("back of the lake") neighborhood and climbed some 450 feet (140 m) to the present-day city of Carlton.

[10] The oldest bedrock visible in Jay Cooke State Park is the Thomson Formation, dating to the Paleoproterozoic era 1.9 billion years ago.

[13] 1.85 billion years ago a mountain-building event to the south called the Penokean orogeny subjected the sediments to intense pressure and heat.

[12] 1.1 billion years ago the Midcontinent Rift System cracked the Thomson Formation, creating southwest-to-northeast trending fractures.

Only small portions of the Fond du Lac Formation are visible within Jay Cooke, primarily along the Little River in the northeast part of the park.

[11][15] Although the rocky riverbed around the swinging bridge is Jay Cooke's best-known feature, this Precambrian formation is only exposed in a portion of the park.

[12] Ice sheets covered Minnesota as many as twenty times over the 2 million years of the Quaternary glaciation, each advance largely obliterating the results of the previous.

This terminal moraine comprises rock and debris dropped at the farthest reach of the Laurentide Ice Sheet's Superior Lobe.

The St. Louis River, flowing into Lake Duluth, dropped its sediment load onto the lakebed, forming layers of silt and sand alternating with clay.

[11] The river's downcutting eventually passed through the Pleistocene lake sediments and into the Precambrian bedrock, exposing the rocky, 13-mile (21 km) gorge that characterizes the western half of the park.

The park houses 173 species of birds including the Pileated Woodpecker, Northern Harrier, and the Great Blue Heron.

It is the longest of the eleven National Scenic Trails and was designed to provide outdoor recreational opportunities in some of the America's outstanding landscapes.

Park rangers offer over 400 naturalist outreach events each year including nature walks, evening campfire talks, snowshoe-building lessons, and geocaching.

program for kids and families, the park provides a number of classes and guides to help with camping skills, canoeing, fishing, archery, and other activities.