Election 2020: How do America's presidential primaries work?

As the Democratic primary race enters its busiest period, John Prideaux, The Economist's US editor, gives his essential guide to understanding the process by which America's presidential candidates are chosen. Read more here: https://econ.st/2IdvpvD Click here to subscribe to The Economist on YouTube: https://econ.st/2xvTKdy For more from Economist Films visit: http://films.economist.com/