Are weights necessary/"svyset" needed for regressions with NHGIS data?

I’m trying to do regression analysis between different geographic levels in the US. I’ve chosen NHGIS data specificlally over Ipums for this reason. Am I right in thinking that the data is pre-weighted?

If this is the case, would my command in stata need to use svyset or am I okay to treat this data as a panel?

The IPUMS NHGIS project provides aggregated data in the form of tables. Thus, you are right that it does not need to be weighted like the microdata available through other IPUMS sources. Regarding treating your data as a panel: As long as your panel is of aggregated data across geographic areas over time, you can consider this data a panel. At the individual level, on the other hand, US Census data is a repeated cross-section.