The paper Eight Americas: Investigating Mortality Disparities across Races, Counties, and Race-Counties in the United States, has this fascinating map (reformatted a bit):
As you can see there is a great deal of variance in white male life expectancy in the United Sates. Compare to this map:
“American” is probably just Scotch-Irish in this case. It is noticeable it seems on this map that the countries in central Texas where Anglo ancestry is dominated by those of German origin exhibit high life expectancy.
In any case, you can actually look at the county-by-county data set from the above paper in regards to life expectancies. The minimum male life expectancy in any county is 62, with the maximum being 80.30. The median is 73.60 and the mean 73.38 (these data are ~2000). There’s a “long tail” of sparsely populated counties with low male life expectancies as evidenced by the lower mean value than the median. The standard deviation across the counties is 2.35 years.
As can be seen on the first map there is a strong geographic component to the interregional differences. Below is a chart which reports the proportion of counties in the 50 states which have a life expectancy at, or above, the Canadian national value as of the year 2000 (again, both these values are for males).
Some states obviously have very few counties. But Kentucky has 120. None of them are at the Canadian level.