Anxiety over threats of political violence is running high heading into today’s election in the US, with authorities across the country taking unprecedented measures to protect both election workers and the ballots themselves.

A security fence rings a Las Vegas building where a Nevada county tabulates votes. An Arizona sheriff has his department on high alert to guard against potential violence with drones and snipers on standby.

Security experts stress that the nation's voting infrastructure is highly secure, and that isolated voting issues do not indicate widespread election fraud. For coverage of each race, see our election updates.