New Hampshire's primary rarely picks presidents but can still be influential

The New Hampshire presidential primary is Tuesday, and despite Donald Trump's commanding win in the Iowa caucuses — and his persistent lead in polling around the country — the race for the Republican nomination is not quite over yet.

In the last 20 years, not a single GOP winner in the Iowa caucuses went on to become president of the United States. But New Hampshire, which has long been the first primary in the country, offers one exception for conservatives in that same time: Trump himself.

His win in 2016, after narrowly losing in Iowa, was the first sign of how the party's voters were rallying to him on his way to the White House.

Trump is on track for a repeat victory on Tuesday, if the polls are accurate. Rival Nikki Haley has been closing the gap in recent weeks, somewhat, though she still trails by double digits, according to 538's average.

Here's a closer look at the history of the New Hampshire primary and its role in helping pick presidents.

Since 1920, New Hampshire has been the first primary in the country.

Together with Iowa — whose caucuses kicked off both parties' nominating contests for five decades, starting in the '70s and ending this year — New Hampshire has received outsized public attention because it offers the first glimpse at whom voters actually like.

But the state's preferences can be unique: In the last 104 years, there were only seven times that a presidential candidate who won a contested New Hampshire primary went on to the Oval Office.

That list includes Republican Dwight Eisenhower in 1952; Democrat John F. Kennedy in 1960; Republican Richard Nixon in 1968; Democrat Jimmy Carter in 1976, after the start of the modern primary system in which voters have a more direct role in selecting nominees;