As the U.S. frets about counting mail-in ballots in November, some say there’s an easier way to hold an election: voting by smartphone app. After all, Americans already use their phones to order lunch, do their banking, and crown reality-show winners from the comfort of their couches. Why not extend this convenience to real elections?

The idea is not a new one. In Estonia, voters have been casting ballots online for more than a decade while West Virginia has let overseas military personnel vote with an app. But despite such innovations, most Americans still vote much like their great-grandparents did—marking ballots and then stuffing them into a box. Many people believe it’s time for the U.S. elections to enter the 21st century.

“The U.S. is living with a voting system designed 200 years ago,” says Aggelos Kiayias, a cybersecurity professor at the University of Edinburgh.

A number of tech companies are eager to help bring U.S. elections into the smartphone era. Voatz and Democracy Live, for instance, have built app-based voting tools they claim can thwart hackers and make sure voters are who they say they are.

Brad Brooks, CEO of OneLogin, a startup that helps the likes of Uber and Airbnb verify the identity of employees, is among those who say the time for online voting is now. The first step, he says, would be for states to create voter IDs using biometric technology like fingerprints and face scans—tech that OneLogin uses in its own operations. He notes the federal government has already adopted such a system for its Global Entry program, which lets travelers pass through airport security more quickly. “If companies and governments are already using this technology to verify identities and give access to information, it’s a no-brainer to use it in the voting process,” Brooks says.

AGGELOS KIAYIAS, CYBERSECURITY PROFESSOR, THE UNIVERSITY OF EDINBURGH.

But election and security experts agree that Americans won’t be voting Estonia-style anytime soon. Any tech upgrade will instead be incremental, they say, and online elections, if they ever happen, are decades away.

One reason is that, unlike a tiny Baltic country, the U.S. is enormous, and its elections are controlled by a patchwork of state and local governments. This would make implementing a national Internet voting system a daunting legal and logistical challenge. Even a basic national voting ID card, used by many countries to ensure the identity of voters, is, for many politicians, a nonstarter.

Furthermore, some voting-tech vendors have spotty track records, making election officials wary of moving too quickly. Who can forget the Iowa caucus in February, when a little-known firm called Shadow built an app for Iowa’s Democratic Party to report vote counts? The app failed spectacularly, resulting in an election-night fiasco and a weeks-long delay before the vote count was certified.

Liz Howard, an attorney with the nonpartisan Brennan Center for Justice who worked as a senior election official in Virginia, has her own horror story to tell. Amid an equipment failure during one election, she tried to get help by calling the vendor responsible—only to have the company hang up on her.

But of all the stumbling blocks to app-based voting, perhaps none is bigger than security. Online ballots would be an irresistible target for state-sponsored hackers, especially those from Russia, which has repeatedly tried to infiltrate U.S. election systems, and in some cases has succeeded. Invariably, voting-tech companies claim their systems are secure. But U.S. election officials have so far balked at putting those promises to the test on a large scale.

Instead, many states have been slowly upgrading their voting technology, without much fanfare. Poll workers in a number of places now use iPads and laptops rather than paper records to check voters against registration lists—speeding up the time required to cast a ballot. Likewise, Travis County, Texas, and Washington, D.C., are creating online dashboards that voters can check from home to see wait times at polling locations, so they can avoid long lines.

Of all the companies creating technology specifically for elections, Microsoftis likely the biggest. Earlier this year during local elections in Wisconsin, it tested software that encrypts ballots after voters mark them electronically or when poll workers scan paper versions. The process prevents tampering while also providing poll workers with a backup vote tally. “Humans are horrible at counting things,” says Tom Burt, the vice president who leads Microsoft’s nascent initiative to supply free election tools.

Microsoft’s technology also provides voters with a code on a piece of paper that they can later use online to verify whether their ballot has been counted and not altered. It’s a step further than elsewhere, such as in San Francisco, where voters can merely check whether their ballots have been received.

As with most things, the adoption of election tech ultimately hinges on funding. Recently, the federal government provided grants to cities and states to upgrade their systems. The awards, however, were insufficient to pay for major projects. One reason for the lack of money is that political will to invest in voting infrastructure typically evaporates after voters go to the polls.

Meanwhile, election-tech makers face their own financial constraints. To make the big improvements necessary for online voting to become feasible, they need cash for research and development. But because the market for their products is relatively small and purchases are sporadic, those vendors generally spend little on innovation.

The upshot is that much like flying cars, a vote-for-President app is likely to be something Americans talk about for decades but may never see.

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Digital democracy

A handful of places have tried online voting. Here’s how it turned out.

Estonia

The Baltic country debuted online elections starting in 2005. Today around 30% of the country’s 1.3 million citizens use the Internet to vote.

West Virginia

In 2018 the state’s overseas military members were able to use phones and tablets to vote in the midterm election; 144 troops in 31 countries actually cast ballots online.

Switzerland

After testing online voting at the local level, the country proposed taking it nationwide. But after researchers discovered a vulnerability that could alter ballot results, officials canceled those plans in 2019.

A version of this article appears in the October 2020 issue of Fortune.