Widespread predictions that Democrats would win the majority in the House and that Republicans would maintain control of the Senate proved to be true. Democrats picked up more than the 23 House seats they needed, while the GOP expanded its grip on the upper chamber.
Here is a look at some of the highly anticipated House races that were crucial to the Democrats' success.
Kentucky 6th District
This was one of the places with an incumbent Republican on the ballot that Democratic strategists targeted. Based on conventional wisdom, Rep. Garland “Andy” Barr should have had little trouble securing another two-year term. The Washington Post noted that the Republican had received at least 60 percent of the vote in his previous two House elections, and that President Trump won the district by 14 percentage points in 2016.
Barr aligned himself with the president's agenda. Democrats found a competitive candidate in Amy McGrath, a former Marine Corps fighter pilot who raised $3.65 million in just three months.
Many observers believed that if McGrath could just come close to upsetting her favored opponent, it would be a good sign for Democratic hopes of a nationwide “blue wave.” That is exactly what happened, as Barr eked out a narrow victory.
Virginia 7th District
In another bellwether contest early on election night, Republican Rep. Dave Brat lost his seat to Abigail Spanberger. As a former CIA officer, the Democrat apparently was not too liberal for the right-leaning district.
Spanberger distanced herself from fellow Democratic candidates who advocated “Medicare for all” and other progressive ideas, while Brat’s continued support of President Trump may have alienated some independent voters. The district is not as conservative as it once was.
Virginia 10th District
Elsewhere in the Old Dominion state, Jennifer Wexton beat Sen. Barbara Comstock. The Democratic state senator deprived the GOP incumbent of a third term in a district that Clinton won by 10 points in 2016.
Thousands of federal government employees, who were wary of Comstock's vow to shut down the government in pursuit of Republican objectives, live in the district. Wexton capitalized on the support of many of those voters, as well as most white women with college degrees. Her calls for stricter gun-control laws contrasted sharply with Comstock, who received almost a million dollars from Second Amendment groups.
New York 22nd District
Republicans knew that to keep control of the House, they would have to win in places like New York’s 22nd district that voted for Trump two years ago. Instead, Democratic challenger Anthony Brindisi knocked off the GOP incumbent, Claudia Tenney.
The state assemblyman raked in more campaign contributions than Tenney, despite fundraisers for the Republican by Trump, Vice President Mike Pence and House Speaker Paul Ryan. Shortly after state officials deemed Brindisi the winner, 50 percent to 49 percent, Tenney announced she would not concede the election until all absentee ballots are counted.
Brindisi presented himself as a moderate, promising to oppose California Rep. Nancy Pelosi's likely bid to become House speaker. Tenney was vulnerable because she has held the seat for only two years.
New Hampshire 1st District
An open seat created by the retirement of Carol Shea-Porter remained in Democratic hands. Chris Pappas will be the only openly gay politician New Hampshire has ever sent to Capitol Hill. He prevailed over Republican Eddie Edwards, who would have become the state's first African-American member of Congress.
Edwards, who fully embraced Trump, held campaign events with presidential lawyer Rudy Giuliani. Pappas depicted the election as an opportunity for voters to reject the president's policies. The district is a swing seat that Shea-Porter and Republican Frank Guinta took turns holding the past 12 years.
Thirty-five Senate seats were on ballots across the country. Democrats were at a disadvantage because they had to defend 26 of them. Republicans, who held a slim 51-49 edge in the chamber, overcame adversity (like incumbent Dean Heller's loss to Democrat Jacky Rosen in Nevada) to increase their majority.
The Democrats' meager hopes of taking control of the Senate suffered a setback fairly early Tuesday evening, when Indiana officials declared that Republican Mike Braun had defeated incumbent Joe Donnelly. The final polls before the election showed the race in a virtual dead heat, even though Indiana is mostly conservative.
In Florida, a large swing state where two veteran politicians faced off, the Senate race was in doubt until the wee hours. When the dust cleared, Republican Gov. Rick Scott emerged as the winner over Democratic Sen. Bill Nelson.
Missouri voters decided it was time to replace 12-year Democratic Sen. Claire McCaskill, who lost to Republican Attorney General Josh Hawley 53.2 percent to 43.7 percent despite her huge fundraising advantage. Running in the GOP-leaning state, which favored Trump by 19 points over Clinton, is always a challenge for even moderate Democrats like McCaskill.
Nowhere were Democrats more disappointed than in Texas, where upstart Beto O'Rourke fell just short in his attempt to upset Republican Sen. Ted Cruz. When the race began, few observers thought the Democrat had a chance, since Texas has elected only GOP senators for decades.