[dmurray]

Are the apportionments done based on the number of census forms returned, though, or based on the Census Bureau's best estimate of population? Presumably the Bureau have a better guess than that, using an adjustment factor that could be different for each state.

[ajross]

Apportionment is based on direct census count only. Indeed there is better science available for population estimation (and IIRC some of it indeed gets done by the Census Bureau's reporting), but that's not how the law was written.

[thechao]

It's called the "American Community Survey" (https://en.wikipedia.org/wiki/American_Community_Survey). It's a great piece of high-quality, modern, scientifically valid demographic work that the C.B. does between its enforced stints with 18th c. `demographicology' that the constitution requires.

[diebeforei485]

Apportionments (and redistricting) are done every 10 years based on the actual census enumeration.

This is required by the constitution: Article 1, Section 2, Clause 3 - as amended by the 14th Amendment.