Federal censuses are private for 72 years; the 1930 census is scheduled for
release in 2002. There never was a restriction on State Censuses that I've
heard of. I believe that the census was taken in all counties extant in the
census year, but all the State copies were lost in the 1911 Capitol fire and
some of the County copies were just plain lost. One town that I know of has
its copy of an early census that does not exist for the whole county. There
may be others. All the original 1915 and 1925 copies exist and are in the
custody of the NYS Archives.