2018 Election: Primary results in California, Iowa, New Mexico, Montana, Mississippi, Alabama and North Dakota

New Jersey isn't the only state that held midterm primary elections on Tuesday. Seven other states — California, Mississippi, Alabama, Iowa, Montana, New Mexico and South Dakota — also voted to determine party nominations ahead of November's midterm elections.

>> READ MORE: Recap of New Jersey primary results

In California, nearly 120,000 voters in Los Angeles County were mistakenly omitted from voting rosters due to a printing error, according to Los Angeles County Registrar-Recorder/County Clerk Dean Logan. Those voters were directed to cast provisional ballots.

Among those left off the voter rolls was actor Henry Winkler, best known for playing Arthur "Fonzie" Fonzarelli in Happy Days.

Here are four key takeaways from Tuesday's primaries:

• In California, Democrats avoided being forced off the ballot in seven Congressional districts won by Hillary Clinton in the 2016 election, increasing the party's chances of winning back the House in November.

• Also in California, longtime Democratic Sen. Dianne Feinstein easily fended off a primary challenge by state Sen. Kevin de León from Los Angeles. But due to California's unusual primary system – dubbed a "jungle primary" – the two will face off in the general election after de León ended up with more votes than first-time Republican candidate James Bradley.

• In South Dakota, Rep. Kristi Noem won a highly contested Republican primary for governor, allowing her to continue her bid to become the first female governor in the state's history.

• In Missouri, Democrats easily claimed victory in a special election for a Republican-held state Senate seat. It is the 42nd seat Democrats have flipped from Republican control since President Trump took office.

Here's a brief rundown of the results in most interesting and noteworthy primary races from across the country.

As of early Wednesday morning, many of California's key races remained undecided. Mail-in ballots and crowded primary fields mean the final results in some of California's most tightly contested races could still be days away. But Democrats appear to have averted disaster by at least finishing second in primary voting in every competitive district in southern California, allowing them to compete for the Republican-held seats in November.

As many as 10 House races are expected to be competitive in the general election, with Democrats targeting seven congressional districts currently held by Republicans (CA-10, CA-21, CA-25, CA-39, CA-45, CA-48 and CA-49) that Hillary Clinton won during the 2016 election.

The two most vulnerable GOP incumbents in the state — Rep. Ed Royce in the 39th Congressional District and Rep. Darrell Issa in the 49th Congressional District — were among the growing number of Republicans who announced they would not seek re-election in November. As of Wednesday morning, former Republican Assemblywoman Young Kim was up by more than 2,000 votes in the 39th Congressional District, followed by Democratic philanthropist Gil Cisneros. In the 49th Congressional District, Republican Diane Harkey, a Board of Equalization member, and Democrat Mike Levin, a lawyer, finished in the top two and will face off in the general election.

In the 48th Congressional District, incumbent GOP Rep. Dana Rohrabacher remains unpopular in a district Hillary Clinton narrowly won in 2008. But as expected, Rohrabacher ended the night with the most votes in the race. As of Wednesday morning, two Democrats – businessman Harley Rouda and biomedical researcher Hans Keirstead – were both more than 1,000 votes ahead of a second Republican in the race, keeping Democrats' hopes alive of flipping the district in November.

Then there's Feinstein, who has served as a senator for California since 1992. Feinstein easily won her primary fight with de León, the former president pro tempore of the California Senate. But due to California's unusual primary system, the two will face off in the general election after de León ended up with more votes that first-time Republican candidate James Bradley.

According to the Washington Post's Dave Weigel, Iowa is one of just six states that has never elected a woman to the House. That might change following the results of Tuesday's primary.

In the First Congressional District, it looks like state Rep. Abby Finkenauer, who received the endorsement of former Vice President Joe Biden on Monday, easily took home the Democratic nomination. Finkenauer, who at 28-years-old would be the youngest woman ever elected to Congress, will take on two-term Republican Rep. Rod Blum in a district that Democrats hope to flip in November.

In the Third Congressional District, businesswoman Cindy Axne defeated two challengers to take home the Democratic nomination. Axne will face off against incumbent Rep. David Young in a race that's expected to be competitive in the general election.

In Montana's only congressional district, first-term Republican Rep. Greg Gianforte will face off in November against former state Rep. Kathleen Williams, who narrowly defeated attorney John Hennan in the Democratic primary. Despite Democratic enthusiasm, the Cook Political Report rates the seat as "likely Republican."

As far as the Senate is concerned, Democratic Sen. Jon Tester had no primary challenger, but will face a tough re-election battle in a state Trump won by 20 points in 2016. Tester's challenger will be state auditor Matt Rosendale, who narrowly defeated retired state Judge Russ Fagg in the Republican primary.

With incumbent Republican Gov. Susana Martinez forced out by term limits, Democrats hope to turn the seat blue in 2018. Rep. Michelle Lujan Grisham, who is leaving behind her safe seat in Congress, easily defeated two challengers to win the Democratic primary. Grisham will take on Republican Rep. Steve Pearce, who is also leaving Congress in an attempt to become the state's next governor.

As far as House races are concerned, only the Second Congressional District is expected to be somewhat competitive in November. Water attorney Xochitl Torres Small easily secured the Democratic nomination, while State Rep. Yvette Herrell fended off three Republican challengers to win the GOP primary.

The most interesting race in the Mount Rushmore State Tuesday night was the Republican primary for governor. Rep. Kristi Noem, who is attempting to become the first woman ever elected governor in South Dakota, defeated Attorney General Marty Jackley to secure the Republican nomination. Noem will face Democratic state Sen. Billie Sutton in November.

The Magnolia State isn't expected to have any competitive House races come November. Two Democrats — state Rep. David Baria and venture capitalist Howard Sherman (who is married to Emmy-winning actress Sela Ward) — will face a runoff after neither garnered enough votes to secure a primary victory outright. The winner will face incumbent Republican Sen. Roger Wicker, who is expected to easily defeat whichever Democrat opponent he ends up facing.

Like Mississippi, no elections in Alabama are expected to be close in November. But in the Second Congressional District, incumbent Republican Rep. Martha Roby failed to win the nomination outright and will face a primary runoff against former Rep. Bobby Bright. Roby, who is hoping to avoid becoming the next congressional incumbent to lose a primary, has been taking heat in the race over her criticism of then-candidate Trump following the release of the 2016 Access Hollywood tape.