Donald J. Trump’s progress in national polls has done something in the 2016 presidential race that is unusual. It has made the Electoral College matter.
Usually it doesn’t. Because voter preferences are distributed relatively evenly across the United States, modest advantages in the popular vote usually translate into substantial majorities in the Electoral College.
If Mr. Trump draws within 1.5 percentage points of Mrs. Clinton in the popular vote, according to calculations by Harry Enten at FiveThirtyEight, he would win 266 electoral votes under current patterns of support for the candidates. By tilting any of three additional battlegrounds — Colorado, New Hampshire or Pennsylvania — he would win the presidency.