This is very weird comment. Are you saying that the USA was not a multi-ethnic/multi-religious state in the 1960s?
In a nation state, politics tend to be divided more on ideological and regional lines, because everyone shares an identity.
There has never been a "nation" where everybody shares an identity in the sense discussed above.
The comment makes sense, but the US isn't best example. Although last century the US was somewhat dominated by one identity (which is now waning and leaving room for others to grow) it has always been multi-ethnic and multi-religious.
A better example would be European nations like Hungary, which have reinforced their national identities in the face of the recent migrant crisis.
We've asked you repeatedly to stop doing ideological flamewar on HN. A crazy number of times actually. Would you please really stop now so we don't have to ban you?
If you define "British origin" to include Irish Protestants, which is reasonable.. But the country was barely 50 years old by the time that cultural hegemony started eroding as German, Dutch, Irish-Catholics, etc poured into the country.
There's even an infamous 1899 political cartoon that asks "Why should I let these freaks cast whole votes when they're only half American?"[1]
The fact is, the US has spent a majority of its existence feeling like there's an immigration and/or integration crisis, starting in the mid-1800s with Irish-Catholics and stretching to the modern day with Latin-American immigrants.
In a nation state, politics tend to be divided more on ideological and regional lines, because everyone shares an identity. There has never been a "nation" where everybody shares an identity in the sense discussed above.