Hillary Clinton never campaigned in swing state Wisconsin in 2016. Kamala Harris isn't making that mistake.

• Kamala Harris and Tim Walz took a short trip to Wisconsin to headline a rally during the DNC.
• The Democratic ticket took advantage of the key swing state's proximity to Chicago to stump there.
• It's a huge contrast with 2016, when Hillary Clinton skipped over campaigning in the state.

As thousands of Democrats from across the country took in the second day of the Democratic National Convention at the United Center in Chicago, Vice President Kamala Harris — the party's newly minted standard-bearer — beamed in remotely from a massive campaign rally in Milwaukee.

Why would Harris choose to be in Milwaukee when the party's biggest showcase of 2024 was transpiring just one state away?

While Harris could have remained in Chicago for the duration of the convention, she and her running mate, Gov. Tim Walz of Minnesota, are on a mission to win Wisconsin in November.

It's the sort of tactical move that could easily be overlooked amid the festivities at the DNC. But it reflects how the party remains haunted by 2016, when former Secretary of State Hillary Clinton didn't campaign in Wisconsin as the Democratic presidential nominee and narrowly lost the state that year to then-Republican nominee Donald Trump.

This is why Harris' rally in Milwaukee was so significant:

Leaning into the Midwest

Unless there's a seismic political earthquake on the horizon, the Harris-Walz ticket is set to win Illinois decisively in the fall.

But Democrats are aiming to carry Michigan and Wisconsin, as both states remain foundational to the party's "blue wall," which Trump breached in 2016 en route to defeating Clinton in the Electoral College.

The Harris campaign sent a clear message by holding the rally in the most populous city of one of the most important swing states. And to put an exclamation point on the roughly 15,000-person event, it was held at Fiserv Forum, which just last month hosted the Republican National Convention.

A key goal for the Harris campaign is to strengthen her standing in Wisconsin. If Harris can recreate former President Barack Obama's formula of boosting Democratic turnout in Milwaukee and Madison, while appealing to union workers, suburbanites, and rural swing voters, she'll be well on her way to winning the Midwestern state.

Since Harris' campaign launched in July, she's visited Wisconsin three times, including her most recent appearance in Milwaukee. And on Tuesday, she took advantage of the city's proximity to Chicago to boost her visibility beyond the confines of the Democratic convention.

Democrats haven't forgotten about 2016

When Trump formally entered the political scene, his campaign zeroed in on working-class voters who backed Obama in both 2008 and 2012. In 2016, Trump succeeded in peeling off just enough voters to deny Clinton victories in Michigan, Wisconsin, and Pennsylvania, which essentially cut off her path to the White House as she also lost Sun Belt states like Arizona, Florida, and North Carolina.

Clinton's campaign eight years ago had no issue touting the historic nature of her candidacy, which meant she could become the first-ever female US president. But Harris has seemingly reflected less on that "first" and has focused squarely on the politics of the moment as she leads a new ticket following President Joe Biden's exit from the 2024 race.

In 2016, Clinton lost Wisconsin to Trump by a 0.77% margin, or by roughly 23,000 votes out of nearly 3 million ballots cast.

Four years later, Biden defeated Trump by a 0.63% margin, with about 21,000 votes separating the two men and nearly 3.3 million ballots cast statewide in the presidential race.

With these razor-thin margins in mind, Harris is looking for every vote that she can get in Wisconsin. And Trump isn't far behind.