People here are exaggerating the fatness of the average American. Yes, obesity is an unsightly problem, but the man in that photo would still be a stand-out today-- just less of one. Instead of being someone we'd only see in a circus, he's the noticeably obese fat guy in the line at McDonalds.

He's definitely not sideshow-freak material today, but he'd definitely be the fattest person on an average subway car. I'd eyeball him at 350-400 pounds.

Also, one thing to keep in mind regarding the rightward tail is that, once you cross into the 400+ pound range, you're at constant risk of weight-related death, regardless of age. We can now keep people at that weight alive into their 50s and 60s at 500+ pounds. A hundred years ago, most of them would have died long before getting to the "circus-worthy" range (700+) today.