>Urban centers through most of human history have lacked a lot of open spaces For most of human history transportation through urban centers was done primarily

>Urban centers through most of human history have lacked a lot of open spaces For most of human history transportation through urban centers was done primarily on foot and roads were designed to facilitate that. Contemporary urban planning is designed around speedily moving motorized vehicles through and the streets, such as they are, are rivers of traffic that pedestrians have to hurry themselves across during the short windows of time that cars aren't speeding by. The invention of the automobile has been terrible for letting kids roam around. On the flip-side of the dangers they face in urban centers, the ones growing up in newer suburban areas lack the density to have an appreciable amount of kids of similar ages within walking/biking distance of each other. Many older style, "streetcar" suburbs do, but we haven't build many of those in the past 30 or so years.