Raking off the back of the Upper Peninsula like a ragged dorsal fin, the Keweenaw (KEE-wuh-naw) Peninsula, though once home to the Copper Culture Indians, was quickly shunned by early European immigrants: Hopelessly remote. Nearly engulfed by Lake Superior. Smothered in snows half the year. Blanketed by impenetrable forests, which grew out of untillable rock and infertile sand. They dismissed it as nothing more than a wasteland, even more so than the rest of the U.P.

But then in 1840, state geologist Douglass Houghton confirmed the presence of copper. Vast deposits of pure, native copper, much of it right near the surface, there for the taking. The young United States had an insatiable appetite for the metal, first for new industrial machinery, and later, for Civil War hardware, electrical wiring, and other innovations. Houghton’s find was as good as gold. Actually, it was even better than gold.

The Copper Rush began almost overnight, first with prospectors, then large mining enterprises flooding the “wasteland” of the Keweenaw. It was the nation’s first mineral rush. Copper employed thousands of immigrant laborers, built cities, made millionaires, and prompted extravagant luxuries like opera houses and “copper baron” mansions. Before it was over, King Copper generated more than $9.6 billion—10 times more money than the California gold rush.

The Keweenaw’s copper legacy still looms large, but in the form of abandoned mines, ghost towns buried in the forest, and the odd juxtaposition of lavish buildings in almost-forgotten towns. Neglected for most of the 20th century, a slow pull finally began in the 1970s to preserve the Keweenaw’s copper heritage. The result is the Keweenaw National Historical Park, established in 1992 (and still very much in development). To be sure, a lot of rich history has been demolished, thrown away, or crushed under the weight of winter snows. But an astounding amount remains, too.

The Keweenaw Peninsula might have its roots in veins of copper, but much of the rest of the western Upper Peninsula traces its heritage to iron. You can read it in the town names—Iron Mountain, Iron River, National Mine, Mineral Hills—and see it on the faces of the residents, an ethnically diverse mix descended from the melting pot of immigrant mine workers. The U.P.’s iron industry stretched from the western border east some 150 miles to the Lake Superior port of Marquette and the Lake Michigan port of Escanaba. It comprised three major ranges: the Gogebic Range, with operations centered around Ironwood; the Menominee Range, based largely around the Iron River and Iron Mountain areas; and the Marquette Range, encompassing Marquette and the Ishpeming/Negaunee area.

Federal surveyors first discovered iron ore in 1844, near present-day Iron River. As workers systematically surveyed this strange landmass recently acquired by Michigan, their compasses swung wildly near Negaunee, where iron ore was so plentiful it was visible even on the surface, intertwined in the roots of a fallen tree. The tree is the official symbol of the city of Negaunee, which itself became completely intertwined with the rise and fall of the iron industry.

Aside from a handful of small mining operations, the unfathomable wealth of the Upper Peninsula’s iron remained largely untapped for several decades, until the ever-expanding web of railroad lines reached the area. In the 1870s, the arrival of the railroad prompted the development of the first major mines in the Menominee Range. A few years later, the Gogebic Range opened. Many of the early mines were open-pit affairs, but soon the need for iron ore drove miners deeper and deeper underground. Today, communities like Ishpeming sit atop a swiss-cheese patch of earth riddled with mine shafts; occasionally, tracts of land sink, leaving behind tilted and abandoned houses.

World War II and its insatiable demand for iron drove area mines to peak production, eventually depleting some of them. By the 1960s and ’70s, the western U.P. iron ranges grew quiet after shipping out nearly two billion tons of ore. All underground iron mines in the U.P. closed by 1978, hurt by foreign steelmakers and the use of more and more plastics in manufacturing.