Is the US under the category of assimilation or pluralism?

Not in the least. The US is the master of culture killing -- or ethnocide.

US richclass, behind the masterful fascistic applications of US richclass legal industrial complex, serves to apply the thickest fascist law books in history over the behaviors and beliefs of a diverse but sucker public. Brainwashed zombies are created anew while practices of plethora aged cultures are trash-canned.

And just turn on US TV for a mere few minutes and you'll suffer more propagandistic brainwashing than people of other nations do in a matter of months.

When smaller groups of people come they often assimilate. When huge hordes come they create pluralism.

Ultra-Protestant sects started the North American colonies becoming the US. They mingled in between the Mongol people first here and established democratic socialist or even communist communities in the 17th century. In the 18th century standard Euro-cultures came ever more.

During the 19th century hordes of British, mostly Irish, and Europeans, mostly German, flooded in. After the Civil War my Irish and German relatives began swarming west. Particularly my Irish relatives led the sweeping away of the Native Americans to make room for ever more overpopulating Euro-culture people coming.

We stopped overpopulating a half century ago but most of the world didn't. Their overpopulated hordes are swarming in again. Worse yet, huge hordes in Asia are literally swallowing the world's economies.

Well, it depends on the area. In more slightly-right-of-centrist regions (liberal regions), they tend to be pluralist, while in more right-wing areas tend to be traditionalist and henceforth, beling in the category of assimilation.

It all depends upon whether we regard our home as a nation and our nation as a home, or mere territory open to all who manage to get here.

The small town carnivals are still good.