How to find out the minimum popular vote percentage a successful US presidential candidate can have?
How to find out the minimum popular vote percentage determine the minimum popular vote that yields a majority of electors in the college?
The answer to this is 0%. It is possible to win one to nothing in enough states that the candidates gets at least 270 electoral college votes, which is enough to win. If a candidate did that in forty-nine states plus the District of Columbia while losing California by ten million to none, that would round to 0% of the popular vote while producing an electoral college landslide (483-55).
Admittedly that is an unlikely result, but it is a mathematically possible one.
In a comment, you explain that you want something more like the method in this answer.
yes, that is close to what I need, but the answer assumes a constant turnout across all states. I would like to use the actual turnover from 2016 November elections. So, my question reduces to: where can I find the actual cast votes per each state (since the algorithm is validated by the linked answer - winning with a one-vote margin the states with the highest ratio of electoral votes per capita.)
If you want the actual votes cast per state in 2016, that's on Wikipedia. It also has the electoral college votes per state, but it removes faithless electors for other candidates. You might prefer to get the electoral college numbers for the whole states.
I threw it in a spreadsheet, and the winner of the thirty-one places with the fewest votes per electoral college vote loses the popular vote by about 79.6% to 20.4%. That assumes that the same number of people vote overall, but they all vote for one of two candidates. In twenty-five places, everyone votes for one candidate. This results in 268 electoral college votes. In thirty-one places, the vote is as closely divided as it can be and still produce a decision.
There are fifty-six places rather than fifty states because the District of Columbia is not a state but has three electors and Maine and Nebraska split off the votes for their five congressional districts.
Note that each state has more than two candidates in the real election of 2016. You could use this to further reduce the margin. Instead of winning a majority, a plurality would be sufficient. So it would be possible to win with 10% or less.