California has a Humboldt County and so does Nevada. There is a Humboldt River and a Humboldt Bay and a Humboldt Current. At least eight towns in the United States are named for Humboldt. And then there is the Humboldt Wagon Road, a “current” interest of mine. Who was this Humboldt and what did he do to get his name all over North America?
It’s not because he explored North America. He never saw Humboldt County (either one) or the Humboldt River.
Baron Alexander von Humboldt (1769-1859) was a Prussian naturalist and geographer. He explored Latin America extensively, and briefly visited the United States. meeting fellow natural philosopher (and President) Thomas Jefferson in 1804.
Having just bought the Louisiana Purchase, the U.S. government was eager to have the opinion, knowledge, and maps of the eminent explorer. Unfortunately, Humboldt couldn’t tell Jefferson much about the newly acquired territory, but they must have had some stimulating scientific and political discussions.
1804 Map of the Louisiana Territory. Note the non-existence of the Great Basin and the conflation of the Sierra Nevada with the Rocky Mountains.
So if he never explored North America, how did we get so many features named for him? (There’s a Humboldt Peak in Colorado too.) Blame John C. Fremont. In his day there was no more prestigious name you could bestow than that of the foremost scientist of the era. What had been called Mary’s River, Fremont renamed the Humboldt River.
When gold and silver were discovered in the Nevada Territory, the northwest quadrant of Nevada became known as the Humboldt Mining District, after the river. And when Bidwell in 1861 began planning a wagon road to take freight and passengers to the Humboldt Mining District, he called his road the Humboldt Wagon Road.
Baron von Humboldt was vastly prolific and influential in the 19th century, and is undeservedly obscure today. An excellent recent book about him is The Invention of Nature : the adventures of Alexander von Humboldt, the lost hero of science, by Andrea Wulf.
goldfields 
Was the Humboldt Mine, located in Michigan’s Upper Peninsula (now closed), named after Alexander von Humboldt?
Roger– I don’t know anything about Michigan, but in the mid-19th century all kinds of places all over the U.S. were named after Alexander von Humboldt. So it probably was named after him.
I read a wonderful book about Von Humboldt by Aaron Sachs, called Humboldt Current. Nineteenth-Century Exploration And The Roots of American Environmentalism. It was printed in 2006. Aaron is currently a professor of history and American Studies at Cornel University