Identify one social factor that influenced american imperialism

One social factor that influenced american imperialism:

Racial superiority is one social factor which can be attributed, not just to America's imperialism, but to any country's imperialism. The Europeans thought and heartily believed that, they are the superior race and it is their duty to improve the lifestyle of the people living elsewhere in the world.

This idea was the reason behind European imperialism while the same idea prevailed when America started its imperialism after its independence. This idea formed the basis for Slave trade too.