I like this comparison of street grids that Daniel Nairn prepared back in 2010:

There’s huge variation here. On the one end you have cities like Carson City, Portland, and Providence, which have small blocks (180′ x 180′ and 200′ x 200′). And on the other end you have cities like Salt Lake City, which have massive blocks (660′ x 660′). 

This variation creates very different experiences for both pedestrians and drivers. It is widely understood that small blocks are better for walking, which is perhaps why Salt Lake City is known as a driving city. (I just learned that they have “crosswalk flags” to help pedestrians safely cross the street. What does that tell you?)

In the case of New York – with its irregular rectangular blocks – it is arguably one of the reasons why the avenues (short side of the rectangle) have such a different feel than the streets (long side of the rectangle). Walking north-south is more enjoyable than walking east-west.

All of this is even more interesting in the context of the point I made in this post: once these urban grids get laid out, they’re pretty sticky. That has far reaching implications.