You can track liberal ascent by sampling the effluent spewed out by the entertainment industry. Norman Lear’s anti-working class All In the Family (1971) is as good an indicator as any of when the cult of liberal virtue signalling achieved supremacy in this country.
All In the Family captures perfectly the social dynamic that propelled the rise of boomer liberalism: the need of upwardly mobile yuppie aspirants to make a public spectacle of their separation from their working class roots. Archie Bunker was a caricature of the working-stiff deplorable. Meathead was … well, Meathead was Rob Reiner playing himself, the prototypical future member of the sanctimonious liberal elite.
Liberalism was and continues to be a means to class segregation. It is snobbery cleverly disguised as sentimental concern for the “excluded,” a category nicely calibrated to not include the disowned working class.
Liberalism’s remarkable achievement was to make the total disenfranchisement of the working class a “progressive” cause. The consequence is that the working class has been left no means of political expression other than the nihilistic embrace of illiberalism. The working class has become subterranean, out of sight, out of mind, except on those occasions when a fissure opens and the stench of the deplorables wafts forth from underground in the embodied form of a Donald Trump or a Roy Moore.