How many cars would I expect to see?

If I were to drive from Ottawa, Ontario to say… L.A., California, how many cars/people could I expect to see provided I take major routes? I want to see if I can turn my car into a billboard and somehow get my voyage paid for.

You might want to check out at

I have no idea if these folks are legit or not. In another part of the site it says

You might want to make sure any ads they put on your car are easily removable. It’d be a bitch to end up with nothing but a bad check and “Hooters” painted in two-foot high letters across your hood…