According to a Friday report in USA Today, since the end of September, the top six markets were Tampa, Orlando, Miami, Philadelphia, Phoenix, and Harrisburg.
Florida -- a perennial swing state enmeshed in a tight contest -- is crucial, with the belt from Tampa to Orlando holding voters from key demographics: the elderly, suburban women, Latinos and military service members.
In targeted ads, the former vice president has focused on health care and the administration's response to the coronavirus pandemic. Alternatively, the president warns voters about a radical left agenda under Biden and compared economic recovery amid the pandemic to his own recovery from the virus.
The non-partisan Center for Responsive Politics says the 2020 campaign is projected to spend a record-setting $11 billion -- about 50% more than in 2016 when accounting for inflation.
In addition, Biden has outpaced President Trump down the final stretch of the race with record-setting fundraising. The Federal Election Commission said that through the end of August, Biden's campaign had raised $540 million while Trump’s raised $476 million.
Working in tandem with their national party committees, Biden raised $365 million and Trump and the Republican National Committee raised $210 million.
All of that money came in before the death of Supreme Court Justice Ruth Bader Ginsburg and a chaotic first presidential debate in Ohio. The advantage allowed the Biden campaign to purchase twice as many television ads in key battlegrounds.
Biden has dominated television ads, spending $223 million since April 9, according to the Wesleyan Media Project. He's also not slowing down.
To both campaigns' benefit, online ads can be tailored to specific regions of a state or to a specific audience.
That said, local television ads are much more affordable.
Still, presidential ads alone won't determine the victor. Trump was greatly outspent by former Secretary of State Hillary Clinton in 2016: $768 million to $398 million. He captured an unprecedented amount of free news coverage, however, and can generate even more as president.