there is no official divider. The only thing that is for sure is where East LA begins, and that's basically anything east of the bridges that join ELA and downtown. That doesnt mean that there is some magical street in between that officially divides the East and West sides of Los Angeles, for the area is much to vast. If you were looking at it in terms of halves, then downtown is part of East LA... but no one would ever call it that. See what I'm saying? There is also this whole area called mid-city but in my opinion that is the west side. Other people think of the west side as being the richer areas of LA like Westwood/Beverly HIlls and such.