It may be the only Beatles concert that didn’t sell out in 1965. August 21: Screaming fans mob Wold-Chamberlain Field (as MSP International was known) when the Fab Four land. But that night, when the band plays Metropolitan Stadium in Bloomington, whole sections of the stands are vacant.

There’s plenty of marketing mojo in the Twin Cities now, but maybe not so much back then. As a new exhibit at the Minnesota History Center explains, local concert promoter Ray Colihan took Minnesota understatement to an extreme. He was afraid the crowd would get too big and out of hand, so he didn’t actually promote the concert—no newspaper or radio ads. Turnout at the 35,000-seat stadium: 26,000.

Exibit will run July 17–September 12.