Pronoun

I'm not sure what you're asking here.

I live in California. It is a beautiful state.
I live in California, which is a beautiful state.
I live in California, where gold was discovered in 1849.

CJ

hanuman,

Note that place names (e.g: proper nouns such as Manchester) are never followed by the relative adverb where.

Not true. You can take probably any well known location and attach "where" to it.

As an example, let's take Vancouver British Columbia in Canada.

Try Googling "Vancouver where" (with the quotes).

I get 57,300 hits.

My friend was born in Vancouver where the winters are warm and where it doesn't receive much snow in the winter.

(edit: The above sentence is a poor example because the symmetry is broken. Perhaps CalifJim can provide a better example.)

MountainHiker

I agree with the people here; you can follow a Proper noun with 'where'.

I live in England, where we all drink tea at 3pm.

I was born in Essex, where all the best people come from, and live there still.

Hanuman,

You will just have to decide whether to believe us or them.

Hanuman,
I think the other site meant to say "where" is not used after a proper noun to introduce a restrictive relative clause. In other words, you can have "Manchester, where ..." (Note the comma.), but not "Manchester where" (Note the lack of a comma.).
CJ