What is it about cities that make people vote Democrat?

[Space7]

Interesting question.

I think all your listed reasons have some effect, but I would also like to add that people who live in cities, as a general rule, have a tendency to be better educated. (Source picture below)

http://www.dailyyonder.com/files/imagecache/story_default/imagefield/2009528.jpg

Teachers in general seem to lean left, and this spills over onto the students.

Educated people seem to become a little bit more lenient towards the redistribution of wealth because they have recent knowledge on important global issues like poverty and the environment, and they end up becoming a little more willing to part with excess wealth to help with healthcare and better education for others.

[Space7]

Are cities overseas (Western Europe/Canada) as liberal as the ones in the United States?

Because Canada is overseas from the United States .

Yes, center-left vote is concentrated into urban areas in Canada as well. Urban centers like Toronto and Montreal have always been the strongholds for that side of the spectrum.

[Space7]

Someone said cities have more educated people? Not in all places. Education is very relative as there's many forms of educated.

True. I was merely referring to the correlation between cities and more school education, as is evidenced by the source picture I included in my earlier comment.

Teachers in general seem to lean left

I take it you've never been to Campbell County.

Can't say I have. Maybe it's only where I live, but perhaps it's because the teachers in my province are upset with our current, right-wing government who keeps slashing the education budget.