The earliest date Trump could lock up the nomination: April 19th

As of Sunday, Trump was about 857 delegates short of the 1,237 needed to clinch the nomination. Even if the New York real estate mogul wins all the delegates awarded through the rest of this month — which is basically impossible — he won’t come out atop the ticket.

In fact, Trump can’t mathematically lock up the nomination until April 19, even if he wins every delegate in every state beginning Tuesday, when Michigan, Hawaii, Idaho and Mississippi will decide.

Though momentum and the element of time matter in campaigns, the schedule of awarding delegates — known as the primary calendar — changes from year to year.

In 2008, for example, John McCain had a seemingly early primary victory on March 4. But because of that year’s schedule, he had actually gone through 39 primary and caucus states, more than any candidate in the modern primary era up to that point.