Bomboy is editor-in-chief of the nonprofit, nonpartisan National Constitution Center.

Modern presidential campaigns target voters down to the county levels, and this fall, it looks like eight counties could swing the battleground states that will decide the November election.

In our constitutional Electoral College system, a presidential candidate needs at least 270 electoral votes to win the election. Ten states are still up for grabs, according to current polls, and one other state with key electoral votes may come back into play.

But a look at where money flows to televised campaign ads shows that the Obama and Romney camps are focused on strategic counties within those states.

Pennsylvania could be a late factor in the election if the GOP decides to put money into a last-ditch advertising effort to complement a grassroots campaign.

Ohio and Florida are traditionally the key swing states that help determine national elections, and the 2012 campaign doesn't appear to be any different.

Cleveland is the target of the second-most campaign spending of any city in America, with $24 million in TV spending so far, but it is two western Ohio counties that are critical to the Romney campaign. (Cleveland TV stations actually broadcast to 19 counties.)

Columbus' Franklin County and Cincinnati's Hamilton County have received a combined $22 million in spending, and these are areas where the GOP contender must do well to counter Obama's strength in the northern and eastern parts of the state.

In Florida, Hillsborough County and the Tampa area have received about $24 million in TV ad spending, while Orlando and Orange County has seen $20.4 million.

Combined, Ohio and Florida have 47 electoral votes, and President Obama would have a big advantage if he can take one of the two states. A loss in either state for Romney could be fatal.

The above spending numbers come from a Washington Post analysis of public data.

A different study from Wells Fargo analyst Marci Ryvicker uses different math for TV ad spending but shows similar results.

Ryvicker has Cleveland as the top market and Washington, D.C., as the second-biggest hot spot for spending. The Washington Post has D.C. edging out Cleveland as the biggest national target for ads.

Technically, the District of Columbia isn't a county, but the heavy spending in the Washington area shows how important Virginia is to both candidates.

But it is a sleepy county in southern Virginia that will get a lot of attention, as third-party candidate Virgil Goode battles to stay on the presidential ballot.

There's even a highway named for Goode in Franklin County, an area affectionately known as the nation's moonshine capital.

One summer poll had Goode taking up to 9 percent of votes in a three-way contest with Obama and Romney in Virginia. Since Goode is a former Republican with a conservative following, some political experts believe he would hurt Romney's chances in Virginia.

Others argue that Goode, who is also a former Democrat, could take some votes from Obama. But it is GOP leaders in Virginia who are contesting his petition to get on the ballot.

So far, the big parties have spent more than $12 million in southern Virginia on TV ads.

The opposite of sleepy Franklin County, Virginia, is Clark County in Nevada, better known as the home of Las Vegas.

Nevada will be a critical swing state late on election night if the GOP and Democrats fight to a draw in the eastern battlegrounds.

One scenario could have the Obama campaign taking just four swing states (Ohio, Iowa, New Hampshire and Michigan) before Nevada reports its results, with a total of 266 electoral votes. Mitt Romney would have 267 electoral votes at that point, assuming he finds a way to win in Colorado.

Nevada has six electoral votes, so the candidate that takes Nevada as the last contested state could win the election.

Clark County controls two-thirds of the votes in Nevada. According to Wells Fargo's numbers, Las Vegas ranks fourth among all cities for spending on political ads.

And then there is a long-shot wild-card market of Philadelphia and one of its pivotal neighbors, Montgomery County.

Pennsylvania is considered as a state leaning toward President Obama and not a strong swing state. But it has 20 electoral votes, and the balance of power in the Commonwealth's government has moved toward the Republicans.

Pennsylvania also has a strong voter ID law that could be in place for the election, and it could affect the turnout in heavily Democratic Philadelphia County.

In affluent Montgomery County, a strong GOP showing could give a big boost to the Romney campaign, especially if voter turnout is high in a county that has the second-highest number of Republican voters in the state.

So far, neither campaign has spent heavily on TV advertising in Philadelphia.

Last week, former Governor Ed Rendell told the Pennsylvania delegation at the Democratic National Convention that the GOP could decide to spend heavily closer to Election Day, and the party couldn't "rest on its laurels."

"If they decide to come in and blitz the last six or seven weeks, they can do it if they want," Rendell said. "And we are going to be outspent. All of a sudden that 9 point lead becomes a 6 point lead becomes a 3 point lead."