The size of a block varies by location and sometimes within a city, but in the eastern United States, five times around a square block is a mile. In this area, there are 20 city blocks per mile.
Cities are not always consistent in the size of blocks. In parts of Denver, there are 16 blocks per mile from east to west and eight blocks per mile from north to south. From the time of the ancient Roman grid systems, there have been super blocks around sports coliseums. These larger-than-normal blocks do not fit the grid system but make room for special uses of land and are still in use in 2014 to make room for universities and convention centers.