While the full election results Tuesday might take a while to emerge, early outcomes in the Philadelphia region could offer clues about which way the fight for the U.S. House and Senate is trending.
Here are the key races and themes worth watching in our region and nationally, and what they might say about the big picture.
The Battlegrounds: PA1, NJ3. The two closest contests in the Philadelphia area are expected in Bucks County and a South Jersey district that includes much of Burlington and Ocean Counties.
If Democrats win both, it'll be a strong indicator that suburban swing seats are breaking their way and that the big gains they need are materializing. The suburbs represent Democrats' primary path to the 23-seat gain they need for a House majority. If Republicans hold both, Democrats might still take the House, but it could turn into a nail-biter.
A split result would be trickier to interpret and might tell us a bit more about what kind of Republican is able to survive.
In Pennsylvania's First District, U.S. Rep. Brian Fitzpatrick has kept his distance from President Trump as he tries to fend off Democrat Scott Wallace. If Fitzpatrick loses, it's a sign that anyone with an "R" by his or her name faces danger, regardless of individual profile.
In New Jersey's Third, U.S. Rep. Tom MacArthur has also campaigned as an independent, but is more closely associated with Trump because he was a vocal supporter of the president's health care bill and tax cuts. He faces a stiff challenge from Democrat Andy Kim.
The Wave Indicators: PA10, PA16, PA11. If there's going to be a Democratic wave, these solidly Republican districts might be the places it shows first. Upset victories for Democrats in any of these races would suggest that they have built enough momentum to go beyond just winning swing seats.
Trump won Pennsylvania's 10th, centered on Harrisburg, by 9 percentage points, but recent polls show a nearly dead heat there between Republican U.S. Rep. Scott Perry and Democrat George Scott. This is probably Democrats' best chance for a big upset in Pennsylvania.
In the 16th, based in Erie County, national Democrats hope Ron DiNicola can unseat U.S. Rep. Mike Kelly. And a recent poll even showed a close race in the deep-red 11th, based in Lancaster County. If Democrat Jess King beats U.S. Rep. Lloyd Smucker there, it might be a tsunami.
Democratic Opportunities: PA5, PA6, PA7, NJ2. Democrats have been favored to flip four open seats in the Philadelphia suburbs and the Lehigh Valley. If they stumble in any of them, it would be a major sign of trouble.
Suburban Democratic women are leading the way in three of those races, an indication of how crucial they have been to their party's push to rebound from 2016.
You can also put PA17, outside Pittsburgh, in this category. Democratic U.S. Rep. Conor Lamb faces Republican U.S. Rep. Keith Rotfhus there.
The Republican Spoiler: PA8. If the day goes sideways for Democrats, this district around Scranton might be a flashing red light. This district embodied Trump's surge in 2016: a traditionally Democratic region where white, working-class voters shifted to back the Republican presidential nominee. That creates a more difficult balance for the incumbent Democrat there, U.S. Rep. Matt Cartwright.
Democrats believe that he is in good shape this year when the national environment favors his party. If they're wrong, it'll be a setback.
The Senate Races: PA, NJ. It could be a role reversal for these two states. Pennsylvania has a Democrat seemingly cruising to reelection, as U.S. Sen. Bob Casey is heavily favored over U.S. Rep. Lou Barletta.
Democrats have instead been sweating in New Jersey, even though the state hasn't elected a Republican to the Senate since 1972. There, Sen. Bob Menendez has a tough challenge from Republican Bob Hugin. Late polls have looked better for Menendez.
Blue Jersey?: NJ7, NJ11. Democrats are hopeful that come January they will hold 11 out of New Jersey's 12 House seats. These two districts — both the kind of affluent, college-educated area that recoiled from Trump — are near the top of their pick-up list.
A turnout surprise? Trump has inspired supporters and opponents in unusual quantities. He defied nearly all predictions in 2016 by attracting people who didn't typically vote or often voted Democratic — as evidenced by his massive winning margins in parts of Pennsylvania.
At the same time, he has also energized critics. Most people thought the Virginia governor's race last year was going to be close — only for Democrats to far outperform expectations in what many interpreted as an early rebuke to the president.
Key governor's races in Georgia, Florida. After Trump captured several states that had been reliably blue, Democrats hope to return the favor by winning the governor's office in Georgia, where Stacey Abrams is trying to become the country's first African American female governor. She is competing with Republican Secretary of State Brian Kemp in a campaign tinged with accusations of voter suppression. An Abrams win would mark her as a rising Democratic star and serve as a counterpoint to a number of GOP campaigns that have embraced racial animosity.
High-profile contests in Florida, Wisconsin, Ohio, and Kansas could also resonate beyond those states. With Washington frequently paralyzed, big states are often the places where ambitious policy agendas are tested, making these gubernatorial seats major prizes. In Pennsylvania, Gov. Wolf is seeking reelection over Republican Scott Wagner.
Senate races in Indiana, Florida, Missouri. While Democrats are on offense in the House, they have a much tougher road in Senate contests playing out in states where Trump won big. Indiana, Florida, and Missouri are races to keep an eye on early — Democratic incumbents are locked in close contests in each of them. Democratic losses would signal that the GOP is likely to expand its 51-49 edge.
But holding their seats is only one part of Democrats' difficult task. They'd also need to win races in places such as Tennessee, Arizona, or Nevada to take the Senate majority.
Other states with key races to watch are North Dakota, West Virginia, Texas, and Montana.
If Hispanic turnout is down on Election Day, it could hamper Democrats in tight House races in Southern California and Texas and in critical Senate contests in Nevada and Arizona.
A realignment. Trump is widely believed to have supercharged a geographic realignment of U.S. politics — and the results Tuesday could confirm it. Suburban areas that frequently voted Republican are moving left. Rural regions where blue-collar workers once voted Democratic have veered toward the GOP. Those trends started before Trump, but have accelerated.
Minnesota might encapsulate the shift. Two rural Democratic seats there could flip to Republicans on Tuesday. Two GOP seats in the Twin Cities suburbs might slip to Democrats. In the fight for the House, those results would cancel each other out, but in the big picture of American politics, it would demonstrate a new reality.