A Census doesn’t happen all at once. While the Census year itself is the most expensive, the Census Bureau has to ramp up for the big count with a decade-long cycle of spending. We can model that cycle by looking at spending each year relative to each decade’s year 1.
For example, the 1990 Census Cycle began in 1981 with $235.1 million (table A). 1982 saw a drop in spending (1981 had included funds to process and publish 1980 Census results). 1983 to 1986 saw budgets more or less similar to 1982. Beginning in 1987, Census budgets rose significantly in preparation for address canvassing in 1988. The next two years saw steep increases as more Census operations kicked in, ultimately culminating in 1990, with a spend of $1.5 billion, fully 6.49 times the 1981 level (table B).
(Data corrected in October 2017)