San Francisco currently has the highest minimum wage in the nation at $10.74. The city wants to make sure its workers continue to be paid the highest in the country.
Residents will vote Tuesday on a proposal to raise its minimum wage to $15 per hour.
If Proposition J passes, San Francisco will become the second U.S. city to mandate that workers will earn at least $15 per hour, the highest rate in the nation and well above the current national minimum of $7.25.
But Seattle got there first, making headlines earlier this year when it approved a plan to gradually raise the city's minimum wage to $15.
Both Seattle and San Francisco plan to phase in the hikes over several years.
San Francisco's proposition calls for the minimum wage to reach $15 by 2018. In Seattle, the rate will go up to $15 for hourly workers at large companies by 2017, while small businesses have until 2021 to make the changes.
Related: Voters to decide on raising minimum wage
About 142,000 workers, or 23% of San Francisco's workforce, would receive a pay raise if the law passes, according to a study by researchers at University of California, Berkeley.
On average, those workers will earn an additional $2,800 a year once the wage hikes kick in.
More than half of San Francisco's minimum wage workers are in just three industries: retail, restaurants and social services, which includes education and health, the study found.
Even if the measure fails, the city's minimum wage is slated to increase to $11.05 next year under a local ordinance that ties wages to the area's consumer price index.
San Francisco says increasing the minimum wage to $15 would translate to an annual salary of $31,000 for full-time workers.
Related: What's the minimum wage in your state?
San Francisco's economy is booming, thanks largely to its proximity to the technology industry in Silicon Valley. But even though the city's unemployment rate is well below the average in California, sky-high property values make San Francisco one of the least affordable cities in the nation.