Kevin Drum proposes a taxonomy of “poor”, “middle class”, “rich”, etc., based on income. I was surprised to discover that I’m upper middle class (albeit at the low end of it).
It was so much easier back in the fifties:
If you drove a Chevy, you were lower middle class.
If you drove an Oldsmobile, you were middle class.
If you drove a Buick, you were upper middle class.
And if you drove a Cadillac, you were well off.