Since 1980 (10 presidential elections), this has happened three times (Anderson in 1980, Ross Perot in 1992, and Ross Perot in 1996). It didn't happen in 2016 with either Stein or Johnson. Will it happen in 2020?
"Third-party candidate" is defined as a candidate that was not nominated by either the US Democratic or US Republican party. Resolution by credible media report as of 9 pm 2020-11-17 California time.