By electorate-at-large, I mean those who are legally entitled to vote in a given election. This includes, of course, a great many non-voters. (Note that, for purposes of this thread, people who are merely unregistered to vote should not be considered "ineligible" on that ground alone.) Massachusetts, for example, gave Lyndon Johnson 1,786,422 votes in the 1964 presidential election. That comes out 76.19% by total vote, but only 53.34% by VAP.
Admittedly, this requires the use of imperfect data.
VEP figures are (to my knowledge) non-existent for the great majority of elections, even counting only presidential elections of the past few decades. Voting-age population figures are accordingly all we have to go on. Even so, the VAP-based percentages are
somewhat meaningful.
