Because for most of its existence, it had a large predominately Western/American minded core of people within it and immigrants coming into it made efforts to assimilate into this core.
Western minded? I hardly count the influx of Poles from Kresy "Western-minded" - they were poor peasants who were essentially of unclear origin. As for "making efforts" - there hardly was much choice in 1900's America - especially given the racism towards those immigrants.
But in case an anti-American like you haven't noticed, America is gradually declining.
America isn't declining - that's just the nonsense spouted by sensationalist media networks. It seems surprising that someone such as yourself, who claims to be "MediaWatch" falls for such simplistic propaganda. Sure, the country might be in a bit of debt - but it's nothing that can't be wiped out quickly by the United States.
Especially with new immigrants coming in that do not want to assimilate and are more loyal to their ethnic background then to America. When America becomes balkanized and large ethnic groups seize American territory for their own ethnic group, like Mexicans seizing the southwest states, America will not be a world power anymore.
I wasn't aware that any American territory was 'seized'. More nonsense spouted by dubious media outlets.
Your not too bright are you?
...
I rest my case.
Poland also by World standards and European standards is not a large nation.
Not a large nation? It's the 11th largest country in Europe - which includes Russia and Turkey. In the EU, it's the 6th largest country by area and by population.
You really don't seem too clued up when it comes to Poland.