For being a cluster f*ck when it comes to traffic, Miami is surprisingly easy to get around with a car. With few exceptions, all the streets and avenues in Miami-Dade County are numbered.
The zero milestone is the intersection of Miami Avenue and Flagler Street in downtown Miami. From there, the county is divided into NE, SE, SW and NW quadrants. Avenues run north-south, while streets run east-west.
Here's a better explanation:
http://www.urbanplanet.org/forums/lo...hp/t16777.html