  We discuss the history and uses of the parallel census technique---an elegant
tool in the study of certain computational objects having polynomially bounded
census functions. A sequel will discuss advances (including Cai, Naik, and
Sivakumar [CNS95] and Glasser [Gla00]), some related to the parallel census
technique and some due to other approaches, in the complexity-class collapses
that follow if NP has sparse hard sets under reductions weaker than (full)
truth-table reductions.
