Here in Southern California, we have a number of Touge hotspots. Closest to me is a quite short, narrow, touge, that is in the hills but flat, and has a corner succession that makes for some great battles. It's very obscure, though, and is mostly frequented only by locals.
Next is a very famous one, Mulholland Drive, which has been a legendary racing location since the 1950s. Due to its infamy, it's not as popular as it could be, but saturday nights, especially in the summer, still see a good number of battles. Plus, driving on the road late at night often yields an impromptu battle.
After that, there are a number of roads in orange county, and that's where the real racing happens.
Most famous is the now closed GMR. GMR, as it is known, was recently a huge racing spot. Some nights, there would be dozens, even hundreds of racers lined up, ready for the downhill. Inevitably, people started making mistakes. There were crashes, injuries, even deaths. These caused the underground location to become known, and the officials got wind of it. They closed it down.
Now, there are several other popular spots. However, I can't say anythign about them, and I have no idea who could be looking at this, and I don't want to jeapordize the security of the areas.