The second half of the 20th century saw a number of developments which have further expanded consciousness in a way that tends to diminish national identity and to allow individuals to see themselves in a broader context.
The availability of recording and communication techniques was the pre-condition for this to take place, and after WWII when states had less need to control their citizenry, people began to take advantage of new freedoms to travel physically and mentally on a mass scale.
It would not be right to say that school primary and secondary education (firmly in the grip of nation states, after all) has played a major role in the cultural expansion we have witnessed in the last 50 years. Curriculi are woefully archaic, and teachers are a highly conservative force in cultural terms. We must look elsewhere for a number of trends that have played their part in the process: a boom in tertiary and adult education, more leisure time, more money, the mushrooming of television content and the introduction of popular air travel are some of the most important of these; and now the Internet will become the most important of all.
Highly educated people tend to sniff at the popular culture that has been created by and for the mass market. There is certainly something rather repellent about the image of an obese, chav couch potato surrounded by empty lager cans, watching reality TV. (Perhaps this is only a British stereotype, in any case.) But that is to disregard the millions of young people who have degrees (even if only in media studies), have done a gap year in some vaguely socially responsible way, are working in a job with prospects, and in a hundred ways have cultural perspectives that enormously outstretch the mental universe available to their grand-parents working in the mine or the fields.