Even a situation in which every Latino voter in America chose the Democratic candidate would mainly allow Democrats to fare better in the heavily Hispanic districts where the party already wins. This is already occurring, to a lesser degree. Over the last decade, Democratic gains among young and nonwhite voters have allowed Democrats to win a majority of the House vote without flipping enough districts to earn a majority of seats.

The Upshot analysis found that if not one of the eight million Hispanic voters supported the Republican candidate, Republicans would lose about a dozen House seats, especially in Florida and California. The loss of those seats would make the Republican House majority more vulnerable if Democrats made gains elsewhere in future years. But given the Republicans’ current strength across rural areas and in conservative suburbs, the loss of every Hispanic every voter would not be enough to cost them the 17 seats that would flip House control.

Those heavily Democratic districts are concentrated in metropolitan areas, while much of the country’s geographical area tilts Republican — and is still heavily non-Hispanic white. In districts held by House Republicans, Hispanics represent only 6.7 percent of eligible voters and an even smaller share of the electorate.