Tonight is the deadline for the completion of census forms by 1.4 million households across the State.
Collection of completed forms by the 4,000 enumerators will start tomorrow, beginning with hotels and guesthouses which have to record every guest who stayed the night before.
Collecting all forms is expected to take a month and by early June the forms will be transferred to a specially-created census-processing depot in Swords, Co Dublin.
By June 2003 the first detailed information is expected to emerge.
One of the anticipated facts is that the population of the State will reach 3.9 million - the highest since 1871.
The Census had been scheduled for last year but was proposed because of the foot-and-mouth outbreak.
Enumerators are bound by the Official Secrets Act and can be fined up to €25,000 if found to have abused information. The Central Statistics Office (CSO) has set up a helpline for householders still without a form for census night.
Staff will be on stand-by to take calls on Lo-call 1890 28 04 02, and the local enumerator will be alerted.