IPUMS-USA data is representative at both the county level and the state level. As with states, a PERWT value of 101 for a given county, IND1950, and OCC1950 combination can be correctly interpreted as 101 individuals (plus/minus a margin of error) residing in that county having that particular occupation and industry. Keep in mind that the margin of error for a small geographic area will be larger than when based on national data, due to the reduced sample size.
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