I do not think we disagree on essentials, but I beg to differ on this one. The US did not wipe the Native population more than Russia did the same to native populations of Asia. Most of the "wiping" of the American natives occurred due to the lack immunity to Eurasian diseases, which was not the factor in Russian colonisation of Asia.
I also beg to differ with the supposed homogenization of the US population. US actively promoted immigration to "solve" its labor shortages problems and fight unionization - which had two major effects:
- it increased ethnic diversity which fragmented any labor movement; and - it changed power relations between owners and immigrant labor in favor of the former (btw, similar arguments have been made about differences between Western And Eastern Europe in the middle ages).
I think that the major difference that contributes to the relative stability of the US is geography. Unlike Russia which constantly faced a threat of outside powers which either invaded or supplied inside dissident groups with resources to destabilize the country, US was geographically isolated and faced very little threat of foreign intervention or infiltration. In fact, 9/11 was the first such infiltration on a noticeable scale in the entire US history. Russia had her 9/11s every decade or so.
Geographic isolation and the absence of any serious foreign threat it produced allowed a high level of elite hegemony in the US, which - ceteris paribus - would be very difficult to achieve in most other countries. Stated differently, it is unlikely that any country built on the level of social inequality that persists in the US to this day would be able to survive largely intact if it were not for it geographic and political isolation.
Wojtek