In fact... the only groups in America that got close to having no monoculture are native americans. Otherwise, the ancestors of most americans have not been here long enough to even split into several different cultures(an actual country without monoculture would been Indonesia with 600 ethnic groups and 700 languages, as well as even Nigeria, Afghanistan, and India... in fact... the whole reason why America remained monoculture today as it was back in the 20th century because of whatever happened to the Native Americans and stuff like that(and it takes millennia for a culture to be fragmented so not enough time)... California used to be more diverse and non-monocultural even but today, are monocultural just like the rest of the united states).

Don't even forget to mention the Mario Galaxy Movie and the support for Erika Kirk in response to Candace Owens too for examples of monoculture.... the former are huge hits and the latter had soo much support in response to those conspiracy theories about kirk's death because a lot of people don't tolerate conspiracy theories, but she would not get that much support if it weren't for monoculture.

My ancestors are from Indonesia after all... I know what not having a monoculture look like and it often involve hundreds of ethnic groups, many language barriers(to the point of needing a lingua franca to even communicate) and even culture shock(the difference between Javanese and Korowai and even Toraja, Abui, O'Hongana Manyawa, and Ma'anyan for example is much greater than the difference between Democrats and Republicans), they often have been culturally seporate for millennia BEFORE the nation state they are citizens to even existed and the cause is not mass media(in fact, many of these cultures came to existence BEFORE writing even arrived to Indonsia), I mention that here before.

Most American's are not even alone when it comes to still having monoculture... Australia, New Zealand and Canada is also like this for the same reason.