Why does squeaky keep Raymond near the side of the city buildings?

Squeaky always looks out for her older brother Raymond, who's disabled. She's fiercely protective of her brother, and anyone who has the audacity to insult him in Squeaky's presence had better watch out, because Squeaky will knock them down soon as look at them. She may be "a little girl with long arms and a squeaky voice" as she describes herself, but Squeaky's a tough cookie and won't hear anyone insult her brother over his disabilities.
Sometimes Raymond accompanies Squeaky when she goes out for her exercises. But because of Raymond's disabilities Squeaky has to be super careful and make sure he always stays close to the buildings. There are good reasons for this. Raymond often gets carried away by flights of fancy. He imagines himself to be a circus performer, walking along the curb as if it were a tightrope. If it's been raining, then Raymond will get down off his "tightrope" and splash around in the dirty puddles, getting his shoes and cuffs wet, for which Squeaky will get hit when she returns home. Also, if Squeaker's not there to supervise Raymond, he can dash out into the middle of Broadway traffic to chase away pigeons. So all things considered, it's best for everyone that Raymond stays close to the buildings.