Here’s Why The 2016 Republican Presidential Primary Could Make History

The GOP now has 17 major contenders for the nomination -- former Virginia Gov. Jim Gilmore announced on Wednesday -- breaking the record previously held by the 16 candidates who sought the Democratic Party's presidential nomination in 1972.

Counting presidential contenders isn't an exact science, however. There are hundreds of candidates each election cycle that run for president. And the term "major" is, of course, subjective.

But it's clear that 2016 is shaping up to be a record-setting election cycle. To understand why, it's important to know a little history about the presidential nominating process.

According to Sidney Milkis, a professor of politics at the University of Virginia and the Miller Center, the 1948 Republican primary holds the record for the most candidates -- 15 -- vying for the presidential nomination before the modern primary system was established. (Ultimately, the GOP nomination went to New York Gov. Thomas Dewey who lost to Harry Truman).

But something happened in 1968 to change everything.