My team is working with demographics data across different data sources (some paid sources and some free data sources available online).
Each of these data sources comes with a shapefile and some attributes associated with each demographic area and could be defined across different cuts of time.
However, when we display these attributes to our end users, we wanted to abstract the multiple datasources concept and show zip codes as a single demographic unit.
We were planning to combine the attributes of all the datasources into one single data source and point that to one of the shapefiles (For the time being, we are willing to look past issues related to granularity or precision in the definition of polygon across these data sources.
However, should we be concerned that the ZIP code to actual geographic area might not be consistent across demographics datasources taken across different cuts in time? E.g. Zip code 12345 used to Map to an area in State A till 2010 but points to an area in State B for all datasets after 2010?