"On Election Night in 1980, Ronald Reagan's victories in the East made him the clear winner, even before voting had finished in the West. TV networks declared that Reagan had defeated Jimmy Carter--and Carter had even conceded--while polls were still open in parts of the country.
"'There was an uproar in the West... when NBC News led its two rivals in calling the election for Ronald Reagan at 8:15 p.m. Eastern time, almost three hours before the voting ended in California and other Pacific Coast states,' David Broder wrote in The Washington Post in April 1981. 'There were reports of people leaving the lines outside polling places, of drivers on their way to the polls going home instead. There were accusations from losers of close local races that the broadcasts had cost them the election.'"
Callum Borchers in The Washington Post looks at controversies over voter projections on election day, then and now.