How can anybody say what the best is? Nobody has ridden everywhere and in reality there is great riding all over the continent. But in the spirit of this thread i say Southern California; the center of the dirt bike universe. We have such diversity of terrains too, I have the Mojave desert to the north, Angeles National Forest for 100's of miles of mountain / desert trails local (I am in Los Angeles county), Pismo Beach for riding dunes on the beach (beat that) Ocotillo Wells and world-famous Glamis to the south and Big Bear for the forest mountain trails. This is all around the Los Angeles - San Diego area. This is the mecca, if you want to go buy something from one of the big companies you can just go to their establishment directly, they are all here.
Hey we all have great riding spots but can anyone challenge the massive landscape of terrains that SoCall offers?