Covid-19 has upended the presidential campaign. The latest chapter: On Monday, President Trump threatened to pull the Republican convention (and the jobs and economic development that come with it) from Charlotte, unless North Carolina Gov. Roy Cooper guarantees “immediately” that Republicans can fully occupy the arena.

The Republican National Committee has continually vowed to hold its planned in-person national convention in August, despite consistent public health warnings against large gatherings, and Trump’s threat is just the latest sign of Republicans’ determination to do so. Democrats, by contrast, have delayed their convention from July to the week before the Republican convention and are considering the prospect of remote voting and a more virtual event that would limit in-person interactions. But they, too, seem intent on holding some sort of convention.

Realistically, even if health officials give the parties the green light to hold their traditional in-person conventions, they will probably insist on unprecedented measures to try to ensure some form of social distancing.

The parties’ determination to hold conventions in some form is a reminder that even though some have questioned their purpose in the modern era, the nominating conventions remain a key part of our cultural and political fabric. While their impact has been undoubtedly diminished from the days when the parties arrived in the convention city unsure whom their nominee would be, these raucous gatherings are still iconic political moments that propel a campaign forward and have long helped to democratize American politics.

The roots of the nominating conventions lie with an increase in political activism spurred by the actions of the controversial Andrew Jackson.

Future president Martin Van Buren had considered the concept of national party conventions in 1828. He envisioned such an event would help unify the Democrats, quashing sectional divisions, and organizing the fledgling group into a coherent party full of experienced politicians. But when Van Buren’s Democrats failed to act on the idea, it was left to a third party to make it a reality.

In an attempt to challenge the two-party system by employing better grass-roots organization, the Anti-Masonic Party held the first national nominating convention in September 1831. The concept was in keeping with the Anti-Masonic mantra of increasing democratization and grass-roots political participation. Holding a convention also promised the added benefit of raising the profile of the party and branding it as far more transparent than its opponents.

This strategy worked. The convention both established the Anti-Masons as an independent party in the 1832 election and led to the widespread acceptance of nominating conventions in both the short and long term.

In the aftermath, grass-roots supporters of the National Republican Party (completely unrelated to today’s Republicans), encouraged their leaders to hold their own national convention in December 1831, at which they nominated Henry Clay to oppose Jackson.

In contrast, despite its name and President Jackson’s reputation as a man of the people, the Democratic Party argued there was no need for a convention to nominate Jackson as he was already president. Nonetheless, wanting to preserve the image of the Jacksonian Democrats as being at the vanguard of the movement for increasing democratization, party leaders insisted on holding a national convention for a new vice presidential nominee, a necessity because of the rupture between Jackson and Vice President John C. Calhoun that had come to a head over the brewing Nullification Crisis in Calhoun’s home state of South Carolina.

The Democratic convention was widely mocked by political opponents, especially when Jackson’s confidante Van Buren became the Democrats’ vice presidential nominee in the face of vast opposition within the party. Van Buren’s nomination also lent credence to claims that the convention was a farce that promoted neither participation nor transparency.

But the mere presence of a convention signaled a significant shift in American politics. Previously, parties had chosen their presidential nominees through the long-discredited caucus system, in which party leaders had picked the candidate behind closed doors.

Increasing angst over a lack of transparency had doomed these party caucuses, whereas conventions allowed for more public discussions of party politics. This brought an air of openness and the potential for greater political participation by grass-roots voters. Conventions therefore became the lasting replacement for the party caucus, and an ideal way to encourage party unity and activism on behalf of the presidential ticket.

With the addition of the Democrats’ party platform following their 1840 convention, platforms also became an intrinsic component of unifying a party behind stated values and policies — the fervency of sectionalism in the period before and following the Civil War put special emphasis on platforms, making them of equal importance to the choice of a candidate.

Beginning with the Anti-Masons in 1832, and lasting until 1968, the outcome of the party conventions was far from certain. Delegates gathered to select a nominee, often producing great drama and sometimes surprise nominees. Nominees owed their candidacies to wheeling and dealing and active campaigning for delegates on the convention floor. This practice continued long after Florida initiated the presidential primary election in 1901, and often resulted in a nominee who either skipped the primaries or hadn’t won any of them.

But after violence, protests and dissension marred the Democratic Party’s 1968 gathering, the parties restructured the nomination process, eroding the drama of the conventions. After the Republicans’ 1976 gathering, filled with suspense as to whether President Gerald Ford would be renominated, the conventions became mere coronations for the party’s candidate, an opportunity to unify their parties and build energy and momentum heading into the general election. The choice of a running mate used to be the last remaining element of surprise but in the 21st century, presumptive presidential nominees have consistently chosen to announce their running mate before the convention.

From the 1970s to 2016, the purpose of conventions has primarily been to gain the coveted “convention bounce” in the polls. Even the platforms have seen their importance shift, as candidates use them as more of a mechanism to appease factions within their party than a binding statement of an agenda. President Trump’s advisers have even explored replacing the 58-page platform from 2016 with something that can fit on a notecard — but this risks alienating key constituencies.

The rise of 24-hour cable news has intensified the unparalleled media coverage given to a party during its convention — even as broadcast networks have cut back coverage significantly.

A candidate’s acceptance speech can make or break a campaign — often helping to forge voters’ impressions of the nominee. Modern conventions focus more on image and inspiring voters than any substantive politics. Considering the potential for limited in-person interactions during the 2020 conventions, the priority of image and providing inspiration will be all the more critical — and possibly harder to achieve if there aren’t thousands of cheering, sign-waving delegates. This energy might be one reason that Republicans are so insistent on having a full arena.

Yet, regardless of how many people are in attendance, the conventions will still provide insight into how unified and energized each party is, and how well they’re able to craft a message that connects. While this isn’t the only purpose they’ve had over time, it’s still important, and will help signal which party is in better shape heading into November.