Take Pennsylvania in 2016. Trump got 2,970,733 or 48.58% of the vote. Hillary got 2,926,441 or 47.85% of the vote. The gap was 44,292 votes which was 0.72% of the total PA vote count (or 72 basis points or bp).
So neither Trump or Hillary got 50% of the vote. All that mattered was that Trump has at least one more vote than Hillary. If Hillary lost by one vote, the percentages would have been 48.5778858% for Trump and 48.5778695% for Hillary, or a percentage point differential of 0.000000163%.
I hope that helps.
