I have to beleive this isn't unique to NYC, unless there's some other correlation I'm not getting.
Just good practice not to walk around inside your own home with shoes that walked on who-did-who-knows-what outside your home.
Just good practice not to walk around inside your own home with shoes that walked on who-did-who-knows-what outside your home.
Even poo city San Francisco keeps BART relatively clean in my experience.