How or when did baseball's 7th-inning stretch originate?

ok, we get up to cheer or go for a trough run or even a $7 beer because the vendor is taking too long to come back around. i think we get a lot of movement at baseball venues these days.

so where and when did 7th-inning stretch come from? the chicago cubs? i mean, granted, we cubs fans do embrace the moment. is it celebrated like that anywhere else?

where does 7th-inning stretch originate?