A. When your city's economy and/or crime (and/or all the other factors that cause people to leave) stinks so bad that it's continuing to lose population to the suburbs despite all your best efforts.

I'm a bit confused about the author of that post's insistence that closing a street to cars is "suburban bliss". I would hardly call the thousands of successful examples in Europe "suburban bliss". The fact that it doesn't work in Saint Louis is because people prefer the real suburbs--the one that you can drive to.

Buffalo has a pedestrian street that they want to give back to cars too, as if 50% of the downtown area isn't already devoted to cars. It won't bring life back to downtown Buffalo, and I doubt it will work in this part of Saint Louis either.