Should census be capitalized in every case describing the US Census?

Not always. The government (see link and quote below) says it depends on how it's used.

http://www.gpo.gov/fdsys/pkg/GPO-STYLEMANUAL-2008/pdf/GPO-STYLEMANUAL-2008-5.pdf

"A common noun or adjective forming an essential part of a proper name is capitalized; the common noun used alone as a substitute for the name of a place or thing is not capitalized [...] Seventeenth Census; the 1960 census."