I am using the 2017 American Community Survey 1-Year Estimates. I am unable to reproduce the total population shown in American FactFinder for a given area using the PUMS.
For example, I am interested in the total population of Erie County, Pennsylvania. Using the PUMS data and PUMA geographic identifier, I get a total population of 261,758. But when I search for the population using FactFinder (same survey and year) and select the corresponding PUMA, I get a total of 274,541.
Should I be able to reproduce this value using PUMS, and if so, what might be the cause of the discrepancy?