This story is part of our elections coverage. Read our list of the most important races and ballot measures to watch here.

Ballot measures aren't the only way to raise taxes in Tucson, but they've become a popular method this year.

Next month, voters in the Arizona city will decide whether to raise the sales tax for two separate purposes -- funding early childhood education for the first time and supporting the local zoo. These two measures follow a May vote in which residents approved a half-cent increase in the local sales tax, from 2 cents to 2.5 cents, to fund fire, police and infrastructure.

"We saw the vote for roads and public safety as really showing that people in Tucson believe that a small investment is worth it, if it results in improvements in our city," says Nancy Kluge, president of the Reid Park Zoological Society, which supports the November measure.

Her group's polling shows that people are likely to approve the tax increase for the zoo, but supporters of the early childhood education initiative might not be so lucky. That measure has drawn more organized opposition, including negative advertising from Americans for Prosperity, an anti-tax group funded by the Koch brothers.

"It's a good idea, just a very, very poorly written ballot proposition," says Mike Varney, president of the Tucson Metro Chamber, which is against the measure. "It's written to be a permanent tax, with a low level of accountability."

In November's off-year election, Tucson's pre-K vote is one of the most high-profile measures on local ballots. Most of the decisions before voters involve hyper-local questions such as parcel taxes and construction bonds, including a $1.05 billion, 10-measure bond package in Dallas covering homeless shelters, libraries, flooding and other infrastructure needs. Similarly, a seven-measure package in Denver seeks voter approval of $937 million worth of bonds covering transportation, cultural and health facilities.

One other local measure that might attract outside attention is in Athens, Ohio. There, voters will decide whether to become the sixth city in the nation to decriminalize marijuana.

"The odd-numbered years aren't traditionally very interesting for local ballot measures," says Josh Altic, ballot measures project director for Ballotpedia.

Progressives have increasingly turned to ballot initiatives to move their causes forward in the face of a state-level landscape mostly dominated by conservative Republicans. But mayors and city councils lean more to the left, at least in large cities, so "you don't see the same dichotomy at the local level," says Altic.

That doesn't mean local officials are adopting everything their citizens want.

In Tucson, "we got tired of lobbying this one and that one to start to address early childhood education and decided as citizens to move it forward ourselves," says Penelope Jacks, chair of Strong Start Tucson, which is sponsoring the tax-raising measure.

In Arizona, education is largely a state-sponsored enterprise -- and the state has been underfunding education and failing to embrace new initiatives like pre-K, complains Eric Schindler, president of Child and Family Resources in Tucson.

"Some of our opponents have said that preschool might be a good idea, but if it is, it's not the responsibility of the city to fund it and you ought to take your cause to the legislature," he says. "But the likelihood they'll understand the need to fund early childhood education is remote."

If the half-cent sales tax increase is approved, it would raise $50 million for "high-quality" preschool education. The mayor and city council would create a commission to determine which programs meet the criteria and would be able to fund 6,500 to 8,000 scholarships for 3- and 4-year-olds, according to Strong Start Tucson.

The measure's opponents, however, complain that it doesn't provide a clear definition about what constitutes "high-quality" pre-K education and that the sales tax increase would be permanent.

"Mayor and Council appoint many commissions, but not with the power this commission would hold," the Arizona Daily Star noted in an editorial opposing the proposition. "There isn’t a clear and direct way to hold the members accountable."

Advocates for early childhood education recognized that their chances were better in Tucson than in Pima County as a whole, but that limited their options in terms of financing. If it had been a county measure, they could have sought a property tax increase. As a city measure, the only mechanism available is the sales tax, which has already been increased by voters this year.

"We somewhat reluctantly chose the sales tax as the funding vehicle," Schindler says. "Timing, of course, was not in our favor."

The measure supporting the zoo, meanwhile, is expected to pass. The zoo is a popular attraction and supporters of the measure say it needs additional funding to keep operating safely. Although private donors have generously supported exhibits housing elephants and tigers, they're less excited about writing checks for the sewer and water pipes underneath the animals, says the zoo's Kluge.

"We're struggling with that dichotomy," she says, "of having some really wonderful things, and having others fall apart."

This story is part of our elections coverage. Read our list of the most important races and ballot measures to watch here.