iac/thinker: The US Census updates its figures periodically more than its full enumeration decennial count. Every couple years or so they provide an updated count to account for the changes since the last full census. These counts also include both legal residents and illegal aliens.
Even without considering the Census’ ACS mid-decade updates, you can look at both the 1970 and 1980 decennial census’ to see if the estimates numbers align with those from the office census (which includes all residents, including illegals.)
Furthermore, regarding changes to Brooklyn’s population from 1980 through today in 2018, wouldn’t those population changes potentially affect the psak since the psak is determined based on population?