Why so few ff places in the northeast?

Something I have been wondering about is, why do the western states, at 
least California and Nevada have so many more different fast food 
restaurants then we do in Pennsylvania, New York, and New Jersey?

For example, in California, there are tons of fast food faux Mexican 
places such as Del Taco, Polo Loco, etc. while in the northeast, the 
only one I can think of is Taco Bell. The variety of fast food burger 
places out west is amazing. Just a few off the top of my had: In-N-Out, 
Fat Burger, Whataburger, Sonic, Burger King, McDonalds, Carls Jr., Jack 
In the Box, Hardee's, and Wendays. In my area, its only Wendy's, McD's, 
and BK. For fast food chicken, I think we're pretty much on par east and 
west coasts, but for burger and Mexican joints, there seems like a lot 
of untapped op****tunity here in the northeast.

I wonder why the variety of fast food places is so much better in the 
west coast than east coast? Do any of you have any ideas?