The annual count of Los Angeles County's homeless population will begin Tuesday night in the San Fernando, Santa Clarita and San Gabriel valleys.
During the three-day event, volunteers will fan out to inspect 2,160 census tracts covering most of the county.
The cities of Glendale, Long Beach and Pasadena conduct separate counts.
Officials of the Los Angeles Homeless Services Authority, which oversees the count, are hoping to match last year's turnout of nearly 8,000 volunteers.
A spokesman for the homeless authority said volunteers can register online up until the last minute, allowing time for driving to a deployment site. All counts begin at 8 p.m. except in the Antelope Valley, where a morning count begins at 6 a.m.
Sign-ups are being taken at www.theycountwillyou.org. An assignment to one of the 160 deployment sites will be made based on the volunteer's address.
After an orientation at the deployment site, volunteers will form teams and receive census tract assignments. The teams will record the number of individuals, tents or lean-tos and occupied vehicles they see.
After the count, the homeless authority will tabulate the paper records returned by volunteers and produce statistical estimates for census tracts and communities by weighting the observations with information gained from a survey of homeless people.
Results are not expected to be published until spring.
The count, which is taken in jurisdictions covering the entire United States, is used by the U.S. Department of Housing and Urban Development to apportion homelessness funds.
In Los Angeles County, this year's count will have added importance in the distribution of about $350 million in sales tax revenue produced by the Measure H homelessness tax approved by voters last March.
The county has adopted a principle of dividing the money by region according to the number of homeless people counted.
The homeless authority is a joint endeavor between the city and county, created in 1993. It is the lead agency in the HUD-funded Los Angeles Continuum of Care, and coordinates and manages more than $243 million annually in federal, state, county and city funds for programs providing shelter, housing and services to homeless people.
Here is the count schedule:
Tuesday: San Fernando, Santa Clarita and San Gabriel valleys, 8 p.m.
Wednesday: West Los Angeles, South Bay/Harbor, Eastern Los Angeles County, 8 p.m.
Thursday: Antelope Valley, 6 a.m.; Metro Los Angeles, South Los Angeles, Palisades/Malibu, 8 p.m.