The number of city blocks that equal a mile is different in each city. Because there is no standard length of a city block in the United State, blocks vary in length across the country.
In order to determine how many blocks are in a mile, it is necessary to know the average size of a block in the city in question. Urban planners suggest that pedestrian friendly blocks are 300 to 600 feet long. A mile is 5,280 feet. Using the mean of 450 feet from the recommended 300 to 600 feet range, a mile would be 11.73 blocks.
Length of blocks varies greatly, however. In New York, for instance, a the average city block is about 750 feet in long, while in Philadelphia the average city block is 400 to 500 feet long, and in Portland, Ore., the average block is only about 200 feet long.
So in New York one would only have to walk about 7 blocks in order to reach a mile. However, not all city blocks are square, so it is necessary to factor in the walking direction. If the block in question runs the width similar to that of a rectangular block, then calculation should be adjusted accordingly.