The US is a Western colony in the most profound sense; a colony of the Western mind...a virgin territory where Western concepts could grow to fruition, relatively unopposed by the entanglements of the cultural atmosphere of the Europe from which such concepts developed. Also emphasis should be put on the very word colony in its scientific sense:
A visible growth of microorganisms, usually in a solid or semisolid nutrient medium.
A kind of isolated medium where strange and fantastic growths can come to fruition.
Russia could be also said to have served as such a colony; a relatively nascent state finding its feet in cultural and political terms, and compared to Europe without an historically developed immune system to protect itself from possibly harmful new ideas, though on the other side, this very immune system could act as a sterile defence against valuable injections of new life.
And these ideas, good & bad, set free in America and Russia would re-colonise the Europe from where they had originally emanated. Good in the sense of rights of man and democratic ideals; bad in the sense of the meaningless, degraded worlds of materialistic truthlessness. Someone might argue that the US is very religious still compared to Europe, but in cultural terms its emanations are broadly the same ideological world of materialism that invaded Russia, and the inevitable leakage of truth from life that this entails. No truth exists, everything is relative, the defilement of democratic principles in the exaltation of the lowest common denominator, etc. "The triumph of the antheap", as Dostoevsky described it.
Interesting to see the exact truth-corroding ideas that Dostoevsky was revealing in their true nihilistic light repeated and developing now in the supposedly anti-communistic west, typically under the banner of liberalism, though a parody of the true values this might entail...instead some new system of false values to bow down to. See, for one example, the old Russian Pushkin versus boots Russian argument where the value of art was rubbished, now re-heated like many other old idiocies in the form of John Carey's What Good Are the Arts? Everything turns to dust under this truth-denying ideology.
So summing up, Europe and the world colonised by the return of migrating European ideas.