[PredictorY]

I don't know about software engineers specifically (and I know that this title is abused by applying it to other positions), but I can tell you that both general pay-scales and the cost of living vary quite a bit in the United States, as well as with the type of organization one works for (finance and pharmaceuticals pay above average, nonprofits unsurprisingly pay below average).

Also, the general pay level and cost of living tend to be highly correlated. Those people you've heard about who make truckloads of money in San Francisco? They also pay twice (or more) what people in other American locales do for housing!