Homeless people on Sunset Blvd in Hollywood. | Photo by Ken Hively /Los Angeles Times via Getty Images

A quarter-cent Los Angeles County sales tax to fund anti-homelessness programs appeared to emerge victorious Wednesday by a thin margin, but elections officials said an estimated 294,900 ballots still need to be tallied, potentially changing the outcome.

With all precincts reporting from Tuesday's election, Measure H had 67.44 percent of the vote, just ahead of the two-thirds majority it needs to pass. The measure was short of the threshold much of Tuesday night and early Wednesday morning, but it steadily gained ground as vote-counting continued, and it passed the two-thirds mark only when the final precincts reported.

The vote tally announced early Wednesday showed Measure H with 379,005 votes in favor, and 182,969 opposed.

According to the county Registrar-Recorder/County Clerk's Office, an estimated 79,000 vote-by-mail ballots that were turned in at polling places Tuesday still need to be tallied, along with about 156,000 vote-by-mail ballots that were postmarked on or before election day, about 4,900 damaged or questioned ballots, and about 55,000 provisional ballots.

Provisional ballots are those that were cast at a polling place amid questions about the voter's qualifications.

Elections officials said additional ballots that were mailed on or before Tuesday will still be accepted through Friday, adding to the remaining ballot total.

The first updated vote totals are expected to be released Friday. All votes are expected to be counted by the end of the month.

The Board of Supervisors declared homelessness a countywide emergency and chose the sales tax hike over a number of other funding alternatives, including a millionaire's tax, a parcel tax and a special tax on marijuana.

Supervisor Mark Ridley-Thomas, who has called homelessness "the moral issue of our generation," told City News Service that "Los Angeles County has the dubious distinction of having more homeless people on its streets on any given night than any other county in the United States.

We have a responsibility to fight homelessness and restore dignity to these people who are living in inhumane conditions."

There are roughly 47,000 homeless people countywide, according to a point-in-time count in January 2016. That total reflects a 19 percent increase since 2013, according to the Los Angeles Homeless Services Authority.

The number of homeless people in tent encampments on hillsides, under freeway overpasses or living in their cars on city streets countywide more than doubled over the same time period and account for nearly three-quarters of the total, according to the LAHSA data.

The ballot measure -- dubbed the Los Angeles County Plan to Prevent and Combat Homelessness -- garnered the support of more than 300 community advocates, labor unions, faith groups and other organizations, including the Los Angeles Area Chamber of Commerce and the Los Angeles Times.

The Los Angeles City Council and councils representing 83 percent of county residents endorsed the measure as of late February.

Opponents of the measure argued that the tax increase would fail to make a significant difference in eliminating homelessness and that taxes are already too high. However, there was no organized campaign against Measure H and no argument in opposition was submitted for the ballot.

The quarter-cent sales tax is projected to provide $355 million annually for 10 years.

The absolute numbers are large, but Phil Ansell, director of the county's homeless initiative, broke it down for voters, saying the tax would amount to "an additional tax of one dime on the purchase of a $40 sweater or $1 on the purchase of a $400 television."

The city of Los Angeles' Measure HHH -- to raise property taxes to fund $1.2 billion in bonds for the construction of supportive affordable housing -- passed in November with the support of 77 percent of voters.

But it is the county that has the programs and personnel needed to provide supportive services -- including medical, mental health and substance abuse treatment -- for individuals lucky enough to move into that housing. Emergency shelter and short-term housing subsidies are also required to keep people off the streets.

"We are not here to manage homelessness. We are here to end homelessness," Los Angeles Mayor Eric Garcetti said at a February rally for the county's Measure H.

Most advocates across the country now back a model called "housing first," which focuses on getting people into housing in spite of drug, alcohol or other problems they may have and then offers mental health and substance abuse treatment and other supportive services.

"It's impossible to get your life together if you're on the streets," County Supervisor Janice Hahn said in December, when the board was voting to put the measure on the ballot.

It will cost $450 million annually to provide all the support needed to end homelessness, according to LAHSA and the county board. That does not include construction costs funded by HHH and other sources.

Proponents say voters should understand that homelessness carries high costs in terms of emergency room and jail visits, among other expenses already being picked up by county taxpayers.

"It costs all of us more in one way or another if we leave these individuals in the street," Los Angeles City Councilman Jose Huizar told the county board in December.

The county has promised to create a transparent process for spending the money should the measure pass, envisioning "an inclusive planning process which draws on the experience, expertise and wisdom of cities, homeless service providers and experts, the faith and business communities, formerly homeless individuals and county departments."

The county has committed to hire an independent auditor to report on Measure H spending and to set up a citizens' oversight advisory board to track allocations. A 10-year sunset clause is built in for accountability and assessment.

Measure H will cost Angelenos no more than a dollar a month, on average, and this investment will help 45,000 men, women and children move from homelessness to stable housing within the next five years, and provide them with the supportive services they need to succeed in the long run," Ridley- Thomas said. "We must seize this opportunity to put an end to the crisis of homelessness once and for all."