The Great Gatsby, casual street

Could you please tell me the meaning of "casual" in the following excerpt from the chapter 8 of The Great Gatsby?

The day-coach—he was penniless now—was hot. He went out to the open vestibule and sat down on a folding chair, and the station slid away and the backs of unfamiliar buildings moved by. Then out into the spring fields, where a yellow trolley raced them for a minute with people in it who might once have seen the pale magic of her face along the casual street.

Thank you.