In most US cities, a city block is between 1 ⁄ 16 and 1 ⁄ 8 mi (100 and 200 m). In Manhattan, the measurement "block" usually refers to a north–south block, which is 1 ⁄ 20 mi (80 m). Sometimes people living in places (like Manhattan) with a regularly spaced street grid will speak of long blocks and short blocks. Within a typical large North American city, it is often only possible to travel along east–west and north–south streets, so travel distance between two points is often given in the number of blocks east–west plus the number north–south (known to mathematicians as the Manhattan Metric).