Over the past two years I've hosted several house concerts at my place primarily for bluegrass groups from the Czech Republic. They've been great experiences with both the Malina Brothers and Druha Trava playing 2-sets in my front yard in from to 75-100 concert-goers. Last night I attended my first house concert (outside of my own) in St. Paul, MN with the local alt.-folk group, The Pines, playing. Five hundred (500) people showed up (including the mayor) to a wonderful venue smack dab within the middle of a city neighborhood with each attendee donating $10. All proceeds go to the band with a couple of local sponsors picking up the costs of holding the concert for the home owners so it was a nice evening for the group. Attendance was so large that we were spread out over the backyards of three different homes. You might wonder what the neighbors would think but this was really a community event with everyone in the immediate vicinity pitching in. A great night, great, music, great people, and a wonderful (though jam-packed) venue that calls itself the Grand Oak Opry after the massive oak tree that concert goers sit under.
I'm wondering whether this is something unique to the Midwest or if, as is often the case, events like these have been taking place on the east and west coasts for years and just reaching the Midwest.