Because as it turns out, they were less than stellar.
The Census found that Brooklyn's population grew by just 1.6 percent (39,374 people) since 2000, while Queens registered a miniscule growth rate of 0.1 percent (1,343 residents) over the past decade.
These numbers are certainly hard to believe.
The mayor announced the city would file a formal challenge at a press conference in Central Queens, where lawmakers said individual neighborhoods like Jackson Heights and Corona alone have experienced more growth than what was claimed for the borough as a whole.
Considering their booming Latino populations, this makes sense.
And Brooklyn Borough President Marty Markowitz's suggestion that the borough's Hasidic population alone grew by more than 40,000 residents- the number listed for all of Brooklyn- could also be true.
But these claims, while credible, mask a larger point: an embarrassingly low number of residents bothered to fill out the Census at all. This was especially true in neighborhoods like Williamsburg and Corona, home to large Hasidic and Hispanic communities, where return rates were in the low 40's or even lower, in some cases, according to city data.
Overall, final Census numbers show, Brooklyn's return rate was 65 percent. In Queens it was 62 percent. (The percentage of state residents who participated in the Census was 69, while the national figure was a slightly-better 74).
So while the city's outer boroughs were likely undercounted, it's because four out of ten people decided not to fill out the form.
The reasons for this were two-fold.
Undocumented workers and others feared the information would be shared with government agencies. And everyone else didn't understand- or worse, understood but didn't buy- the idea that a larger population would result in improved government services.
Citizens do have a responsibility to inform themselves.
But elected officials are responsible for untangling government bureaucracy, and explaining to their constituents how services are funded and distributed. Last year federal, state and city lawmakers tried making a case for the Census. They just didn't do a very good job.
At least they have nine years to prepare for the next one.