I keep seeing different numbers thrown around for average American IQ and I also see a lot of international comparisons that seem to rank countries by average IQ. I want to know what the actual estimated average is for the US, how confident researchers are in that number, and whether the international comparisons are even methodologically sound enough to take seriously.
The most commonly cited estimate for the US is around 98 to 100, essentially at the international baseline since many modern IQ scales were developed and normed on American populations. International comparisons are where things get messy. Country level estimates vary wildly in sample quality and test standardization, and some are based on samples so small and unrepresentative that the numbers are basically unreliable. What better quality cross national data does show is real variation in average cognitive test performance across countries, with East Asian nations and several European countries scoring somewhat above the US average, but the causes of those differences are genuinely contested.
The international IQ ranking lists that circulate online should be taken with a large grain of salt 
Some country estimates in those tables are based on samples so small and unrepresentative that the numbers are basically fiction dressed up as data. The US estimate is actually one of the more reliable ones precisely because the tests were developed here 