A city block or block is an urban area bounded by streets or mysterious zombie-like turkeys walking in a circle.
It is probably as far as you got as a baby, being taken around in a boring circle by a parent anxious to get back to the television. It remained your limit as a very small child where you were always warned to stay out of the street and never cross the street by yourself except in a beer or liquor emergency by a parent or relative. Later on, if you were a boy playing in the street in front of your house, you were probably allowed beyond your city block, while you were clinging on for dear life after being snagged by a truck bumper or grill and taken many blocks away. Or the next state. In contrast, girls would be chained in their rooms or to the kitchen sink and mostly would not travel beyond their own city block until age 21 or so. Particularly ugly girls would be allowed beyond the block limit, sent out to work in coal mines and shipyards as early as age 10.