All digital systems are subject to hacking. And that’s equally true for voting machines. Many many States use DREs (Direct Recording Electronic systems) to count votes electronically and most States have a back-up paper trail. But these 5 States don’t have any ability to recount or audit because they only use DREs:

There’s also a bill introduced in the 2018 Senate which is likely to be reintroduced in this Senate called the Protecting American Votes and Elections (PAVE) Act that “requires the use of paper ballots and “risk-limiting” audits for all federal elections.” If passed, States would have no choice but to adopt a verifiable paper trail.

Different States have different solutions. Some States use an electronic voting machine that generates a paper ballot. Other states use only paper ballots to avoid the problem altogether. 19 states allow you to fax or email a ballot. And several States, especially in the West, vote only by snail mail. To see how your State handles your vote, check out voting policy on ballotpedia.org.