Designation of Election Systems as Critical Infrastructure [Updated September 18, 2019] [open pdf - 409KB]
From the Document: "Prior to the 2016 federal election, a series of cyberattacks occurred on information systems of state and local election jurisdictions. Subsequently, in January 2017 the Department of Homeland Security (DHS) designated the election infrastructure used in federal elections as a component of U.S. critical infrastructure. The designation sparked some initial concerns by state and local election officials about federal encroachment of their prerogatives, but progress has been made in overcoming those concerns and providing assistance to election jurisdictions."
CRS In Focus, IF10677
Congressional Research Service: https://crsreports.congress.gov/