A thought occurred to me today. Representation in he U.S. congress is population (House) and geography (Senate) based.

Do any examples exist of a representative democracy that is demographic based? i.e. Women get X representatives based on being 51% of the population. White, Black, Latino, etc get proportional representation. Gay, Straight, Transgender get their representatives.

If so, what works or doesn't work about them?

If not, what would something like this look like?

I'm not really going anywhere with this, other than a thought experiment. Hopefully it's thought provoking.

Cheers.

edit: A little backstory, I was watching The Daily Show with Kristen Gillibrand as the guest and she pointed out that 51% of the population was female and 17% of Congress was female. It seemed a little absurd, but led me to wonder why that is. I mean, the obvious is that originally only white landowners could ever hold office so who cares? But now that things have drastically changed it seems a little silly not to give vested parties a solid, proportional voice. That doesn't really work on a district system.

However, I have no idea how something like that would work... ...