But beyond the history-making nature of her status as the country’s first woman and person of color to be veep, the 2020 down-ballot elections have given Harris another prominent position: With a Senate split 50-50 between Democrats and Republicans, Harris will serve as the body’s 101st, tiebreaking vote.

The U.S. Constitution appoints the veep president of the Senate, and, in the event of a tie, grants her or him the ability to cast the tiebreaking vote. The responsibility is a practical one, with consequences for legislation—but for Harris’s history-making tenure, the role comes with a bonus. “It’s a symbolic recognition of her power as VP,” says Kelly Dittmar, director of research for the Center for American Women and Politics at Rutgers University.

The privilege has been used by some vice presidents more than others; outgoing Vice President Mike Pence has cast 13 tiebreaking votes over the past four years, while President-elect Joe Biden never broke a single tie during his eight years as President Obama’s No. 2.

Quirks of the Senate have determined how often the vice president can swoop in to make a decision in Congress on behalf of the presidential administration. To overcome the Senate filibuster, most legislation requires 60 votes to pass—meaning that in a roughly evenly split Senate voting along party lines, a VP would be unlikely to descend on the Capitol to break a tie.

But in 2013, the Senate abolished the filibuster for executive branch nominations, meaning that such nominees could be approved by simple majority. The shift resulted in a dozen tied votes during the Trump administration, all of which were broken by Pence. (The rule had been changed midway through the Obama administration, but with no ties resulting during the remainder of the term, Biden never had the opportunity to cast a deciding vote.)

In 2021’s 117th Congress, Harris could serve as a tiebreaker on Biden’s cabinet nominations if Republicans as vote as a bloc against his picks.

The first and last time, until now, that the Senate was exactly split at 50-50—making a tiebreaking vote along party lines even more likely—was in 2001, with Dick Cheney in the vice presidency after that year’s inauguration of President George W. Bush.

The frequency with which the Senate requires a tiebreaker vote can also be affected if the two parties’ leaders opt to create a power-sharing agreement, as happened in 2001 and is likely to happen this year. According to CNN, Democrats’ Chuck Schumer and Republicans’ Mitch McConnell are close to finalizing an agreement that would allow Democrats, as the majority party, to set the Senate’s schedule, but would split committee assignments evenly among each party’s senators. Under such a deal, the party leaders would likely attempt to limit the number of votes that would split 50-50, reducing Harris’s role.

Practically, Harris’s responsibility as tiebreaker could also mean she’ll need to stay in Washington and avoid travel when it seems she could be called upon to cast a vote, according to Molly Reynolds, a senior fellow studying Congress at the Brookings Institution.

Harris resigned her own California seat in the Senate on Monday ahead of Wednesday’s inauguration. Her four years of experience in the institution—and working for a longtime former senator in the Oval Office—may influence how she approaches this constitutional responsibility, says Reynolds. “She herself [was] a member of the Senate,” says Reynolds. “She’ll look favorably upon this particular constitutional responsibility.”