15 millennials are running for House seats in primary elections on Tuesday, and 4 candidates are poised to make history if they win

AP Photo/Brynn Anderson

Democratic gubernatorial candidate Gwen Graham thanks a campaign volunteer in Miami Lakes on Aug. 18, 2018.

• Voters head to the polls Tuesday for primary elections in Florida, Arizona, and Oklahoma for a potentially historic vote in state legislatures.
• In these primaries, 15 millennials are running for seats in the House of Representatives, continuing the swell of younger candidates aiming to transform Congress in November's midterm elections.
• Four candidates in Florida stand to set demographic records for state offices if they win.
• Interest in key issues, like gun control in Florida, are encouraging for younger candidates looking to challenge long-seated incumbents.

Voters head to the polls Tuesday for primary elections in Florida, Arizona, and Oklahoma in a potentially historic vote.

Tonight's primaries include 15 millennials who are running for seats in the House of Representatives, and Florida's race for governor could yield some demographic firsts for state offices.

Continuing the swell of candidates gunning to shake up Congress in November's midterms, six millennials are running in Arizona, and eight in Florida, according to Axios.

Four of the Sunshine State's races could make history.

Democrat Cedric McMinn could become the state's first openly gay African-American lawmaker if he wins his race for state representative.

Former state Rep. Gwen Graham and Tallahassee Mayor Andrew Gillum both stand to make history if successful in the race for Florida governor, as either the first woman or the first African-American in the office, respectively.

AP Photo/Chris O'Meara

Democratic gubernatorial hopeful Andrew Gillum speaks to the crowd during a campaign stop on Aug. 17, 2018 in Tampa.

If elected, Rep. Sean Shaw would be state's first African-American attorney general.

But they all have to win the primaries on Tuesday, then the general election in November, if they're going to make history.

The Pew Research Center defines millennials as born between 1981 and 1996, making the age ceiling for the term 37. The average age of a member of Congress is almost 58 in the House and almost 62 in the Senate - one of the oldest in recent history, according to the Congressional Research Service.

Votes in Florida and Arizona will serve as particularly strong examples for changing the status quo, as Democratic groups look for wins with gun control on voters' minds two days after a deadly shooting in Jacksonville.

Since the massacre in Parkland, Florida, Marjory Stoneman Douglas High School students have been leaders on the national stage advocating for stricter gun laws and pushing for more engagement from younger voters.

The parents of two of the students killed in the massacre are running for two Broward County school board seats, on platforms that push improved school safety, which they say was not a priority before the shooting.

Though some younger candidates have grabbed headlines this election season - such as the stunning defeat of a longtime New York representative by 28-year-old Democratic socialist Alexandria Ocasio-Cortez - a surge in youth interest and activity in policy stands to transform the House.

Tuesday's elections are the final multistate primaries before the general elections in November.