Grand Central Station

When one says, "it's busier than Grand Central Station around here".
why do they chose "Grand Central"? And not, say "Union Station", which I'm sure is just as busy?

I'm going to begin a movement (I won't even tell ya where my mind just went with that statement ).....
I'm going to change things up...

It's been busier than Union Station in here this morning!!

(it just doesn't sound right, does it?)

where did "Grand Central" come from? I know it's in New York City, but why do we say that?

What other "sayings" do you remember? Or use?

Susie (new Harley, 5 grandkids, my kids Godmother ), used to say something her grandmother said.... it went something like this: he's got more Columbus than Christopher.
(or something along those lines)