Elsewhere in other canvasses involving close votes on Tuesday, Prop 1 also remained dead in Uintah County by a mere 21 votes after it had trailed by 40 on election night.
It also died in Juab County by 93 votes after it was behind by 101 on election night.
Prop 1 had appeared on the ballot in 17 counties, apparently passing in 10 and dying in seven. Among other places that defeated it were Utah and Box Elder counties, while among those passing it were Davis and Weber counties.
Abby Albrecht, chairwoman of the pro-Prop 1 campaign, expressed disappointment at the measure's failure in Salt Lake County which came even though her group outraised opponents $675,000 to zero.
"Our cities face significant transportation funding shortfalls, mounting maintenance costs and growing populations," she said. "Without Prop 1, local officials and residents will be forced to consider potentially costly alternatives to addressing these needs."
The proposition could reappear in the future in the seven counties where it failed, and 12 others that did not put it on the ballot.
"We will continue to advocate for investment in transportation that keeps our economy moving and communities thriving," Albrecht said. "We need to continue this conversation to find a way to close the gap between transportation needs and financial realities."
Prop 1 will raise sales taxes by a penny for every $4 in purchases in the counties approving it.
Along the Wasatch Front, 40 percent of the money will go to the Utah Transit Authority. The other 60 percent will go to cities and counties for local road and other projects.
Both supporters and critics of Prop 1 said the major reason for its defeat in some areas was controversy about UTA, including a legislative audit last year that criticized the agency for sweetheart deals with developers, high pay and bonuses, and extensive travel by executives.
Evelyn Everton, Utah director of Americans for Prosperity, which opposed Prop 1 by especially targeting the portion that goes to UTA, said Tuesday that defeat in Salt Lake County shows the "Utah Transit Authority needs to get its house in order and be a better steward of taxpayer dollars."
She also said it shows "voters are saying they have had enough of tax increases in one year," after the Legislature raised the gasoline tax by 5 cents a gallon (effective Jan. 1), and raised property taxes by $75 million for education.
UTA has recently made a number of changes aimed at polishing its reputation and winning back public trust. Those include the departure of two former top leaders, a cap on executive bonuses and tighter control and greater disclosure of travel. The agency has won national awards for its work and built an extensive rail system under budget and ahead of schedule.
After the election, UTA leaders vowed to earn public trust and to keep promises to improve service in counties that approved the tax hike.
"We want to continue to let the public know that this current board is making good decisions. They put trust in us to fix some things, and we have been and we continue moving forward," UTA Board member Matt Bell, who is also a Weber County commissioner, said during a UTA committee meeting earlier this month.
UTA Chief Planning Officer Matt Sibul has said that counties that passed the tax could see some improvements in transit service as early as April, when the higher tax kicks in. UTA won't receive any of the money until next summer.
"We're proposing to make most of the additions to service next August. That will be our big change day," Sibul said earlier. "Some of the changes won't be fully realized for a couple of years … because we need to order new buses. It's a good thing, but it takes a couple of years."
Prop 1 results in Salt Lake County
For: 84,035, or 48.79%
Against: 88,198, or 51.21%