Some cities have their streets laid out in a Cartesian coordinate plane, with the "NW", "SW", "SE", and "NE" street designations relating to the four different quadrants. Once you discover the origin (0,0) of the city, you can generally navigate without familiarity of the named streets. For instance, the origin in Portland is Burnside and the Willamette river. So, 1500 SE 40th would be about 15 blocks south of Burnside, on 40th.
This practice is probably more common in cities that were deliberately designed, and younger cities. Unfortunately, this very simple navigation equation can break down when faced with natural topography such as large hills and lakes. (Seattle and Camas, I'm looking in your direction.) Regardless, this concept was immensely enlightening when my dad explained it to me many many years ago.
Tags: driving seattle