DETROIT – Detroit is famous for its music, from the Motown hits of the 1960s to the rap of Eminem. But Michigan was also fertile ground for folk music, brought to the region by immigrants in the early 20th century and played in the logging camps, mines and factory towns where they worked.

Legendary folklorist Alan Lomax discovered Michigan’s music in 1938 on his famous 10-year cross-country trek to document American folk music for the Library of Congress.

A trove of his Michigan recordings is now being publicly released, coinciding with the 75th anniversary of Lomax’s trip. The release is causing a stir among folk music fanciers.

“It was a fantastic field trip – hardly anything has been published from it,” said Todd Harvey, the Lomax collection’s curator at the library.

The 250 disc recordings of about 125 performers, along with eight reels of film footage and photographs, reflect the rich mixture of cultures in Depression-era Michigan.

The recordings weren’t released at the time, in part because the late 1930s were a time of growing suspicion of non-English-speaking immigrants in the United States, said Laurie Sommers, Michigan’s program coordinator for the Lomax project.

Now, the library is releasing a podcast and an e-book, and the University of Wisconsin is releasing a multi-CD set. A traveling exhibit with live concerts will begin Monday in Mount Pleasant, about 120 miles northwest of Detroit.