Ypsi Trivia Question

In perusing some 1906 Ypsilanti Daily Presses, Dusty D learns that in 1906, there was only one business open at night. The only one in town.

It wasn't a saloon--those closed at 10:30 p.m., and weren't even open on Sundays. Or weren't supposed to be. It wasn't a 24-hour gas station, of course, or a 24-hour big box store, naturally. But it was big! In the darkness, when almost all the lights in town were doused, one place burned with light, noise, and energy!

See if you can guess what it was! Answer this evening.