From that point of view, yes, the US is likely more of a 'melting pot' than most of Europe. London is probably close. There's a lot of nuance to it, though - big cities are different than small towns, immigration patterns change over time, and so on.

The melting pot, to some degree, eliminates that diversity, though. After a generation or two, lots of people are unable to speak their parents/grandparents native language. Perhaps that's less true today, with cheap travel, the internet, and people placing more value on diversity and knowing more than one language - it'd be interesting to see some research. Anecdotally, a ton of the older Italian-Americans I've met don't speak Italian much - they wanted to blend in and not be 'foreigners', and only later in life realized that not speaking the language was a loss.

I've lived in both London and NYC. NYC feels more diverse simply because it's a bit strange to have loads of foreigners in the country when we know very well that it's very difficult to enter the country legally, whereas London is about 50/50 british to non-british. Not to mention, GB is comprised of England, Wales, Scotland, so you have that combined with the Aussies, Kiwis, Saffers, Italians, Germans, Irish, Spanish, Russians, etc. Not a day goes by that I'm working with a non-British citizen in London. Couldn't say the same for NYC.

Does racial diversity matter a great deal to you Americans? I find cultural diversity far more significant. Whether you can understand someone, or whether a thumbs up is a positive gesture or a grave insult to them. These things matter a great deal more than whether they have a pink face or a brown one.

When you look at a random central European city, and see Slovenes, Austrians, Turks, Albanians, Greeks, Serbs, Croats, Romanians, Germans, Russians, Poles, Italians, Macedonians, Bosnians, Ukranians, Moldovans, Estonians, Lithuanians, etc etc etc, do you think to yourself "Wow, there's no diversity at all here, is there? Everyone is white!" Then how about any random western European city, where you'll find the same mix, plus immigrants from their former colonies in Africa and Asia, plus the usual North Africans, does that almost meet your standards?

There are some very diverse countries in the world such as India, the Russian Federation, Indonesia, South Africa and DR Congo, all large (former) colonial empires in the old world. Some might even count the European Union, depending whether you think of it as a confederation or not. There is nothing like that in the Americas.

"Does racial diversity matter a great deal to you Americans?"

Given our peculiar history, yes, it means a lot.

Vancouver (and other areas in Canada, particularly Toronto) seems to be making a real go of it though....

[My impression was that in the days after the HK handover, it seemed like half of HK moved to Vancouver (I gather the Canadian government had unusually generous Visa policies), and that apparently really started a ball rolling; the last time I was there, it seemed amazingly diverse.]

Have you been to Toronto or London?

Toronto is great, but I don't see it as more diverse than other big cities in the US, such as Boston, Chicago, or Washington.

Maybe Toronto, Singapore, HK? But yeah I guess NYC and San Francisco are on the top 2.

I'd suggest you spend some time in Melbourne, Australia.

Chicago has some spots diversity on that scale as well.