- Main article: List of Episodes
Officially announced on November 16, 2011, Season Twenty premiered on September 14, 2016. Like Season Nineteen, this season also features a continual storyline. See Storyline below for more details on what South Park was up to in Season Twenty.
|"Member Berries"||September 14, 2016||2001||268|
Mr. Garrison is still on the campaign trail as the National Anthem gets a reboot by an American Icon.
|"Skank Hunt"||September 21, 2016||2002||269|
The boys decide they have to take down Cartman but meanwhile, Skank Hunt takes his rein of terror global.
|"The Damned"||September 28, 2016||2003||270|
Gerald is thrilled with the media attention as he continues to troll everyone and anyone.
|"Wieners Out"||October 12, 2016||2004||271|
Kyle feels tremendous guilt over the rift between the boys and the girls. When he tries to bring them together, things only get worse. The boys finally band together to stand up for their rights.
|"Douche and a Danish"||October 19, 2016||2005||272|
The kids get pulled in to the search for the notorious Skankhunt42. Meanwhile, Gerald joins forces with the other trolls to stop Denmark from launching TrollTrace.com.
|"Fort Collins"||October 26, 2016||2006||273|
An entire city in Colorado gets hacked. Gerald and Cartman may lose everything when their complete history of internet activity becomes public.
|"Oh, Jeez"||November 9, 2016||2007||274|
PC Principal tries one more time to make peace between the boys and the girls. Meanwhile Gerald comes face-to-face with the Troll Hunter.
|"Members Only"||November 16, 2016||2008||275|
Gerald tries anything to escape the Troll Hunter’s revenge. Meanwhile, Cartman and Heidi make their way to SpaceX to try to get on the first rocket leaving for Mars.
|"Not Funny"||November 30, 2016||2009||276|
Cartman is certain Heidi can solve the problem of getting them to Mars because she’s really funny. Gerald tries to save himself by reasoning with the Troll Hunter while Garrison explores his new found military power.
|"The End of Serialization as We Know It"||December 7, 2016||2010||277|
As TROLLTRACE goes live, Sheila logs on to see Gerald’s on-line activity. At SpaceX, Cartman tries to convince the scientists that going to Mars is a bad idea. And defying their mom, Kyle and Ike get all the kids together to try to save the world from certain destruction..
This season's storyline is about internet trolls and the presidential election.
During a volleyball match, the girls sit out the National Anthem in protest of an Internet troll known as Skankhunt42. Kyle, along with the other boys, believe it's Cartman and break his stuff. At the end of "Member Berries", the troll is revealed to be Gerald. At the end of "Skank Hunt", the troll attacks again, making the boys realize that Cartman is not the troll. Gerald starts to troll a woman known as Freja Ollegard, which goes to plan until she commits suicide. Gerald gets scared, only for his fear to increase when he finds a note on his car saying "I know who you are." In response, he breaks all his technology. He then receives an email telling him to meet at Freemont Bridge. When he goes there, he finds out the message was from a troll known as Dildo Shwaggins. He tries to ignore him when he continually asks him to join his group. He even goes as far as saying to Sheila that he was watching "piss porn" instead of trolling, which ends up with Sheila peeing on him. Dildo Shwaggins (or "Dick") shows him a video from BBC News of the TrollTrace.com, which will track all the trolls down. Gerald decides to join Dildo in his troll group. Together, they troll the entire of Denmark, leading the country to quit social media. After they do this, Dildo tries to make friends with Gerald, but he declines rudely. When Gerald discovers the Danish plan to release the internet history of anyone, he tries to ask Dildo for help, but he declines due to Gerald's rudeness earlier. Hillary Clinton meets Gerald under Freemont Bridge to get him to infiltrate TrollTrace. Gerald travels to Denmark, in the disguise of the ambassador. He is put in a room along with the other trolls, who reveal to him that the government had done a deal with the Danish. The briefcases, that were supposed to detonate and bring down TrollTrace, instead play Rick Astley's Never Gonna Give You Up. Lennart Bedrager tells Gerald he can call someone, but he has to reveal his true identity. He calls Ike and tells him to troll as Skankhunt42. Sheila spots Ike trolling and thinks he is responsible for the trolling. Kyle comes home and finds out what has happened. He then works out by what Heidi said before that Gerald is the troll and sets off to find his dad. Sheila brings them back and berates them for what they have done. Meanwhile, Lennart Bedrager reveals to Gerald his true plans. He tells him he plans to set the entire world against each other because it's funny. He then locks Gerald in the room, as both the trolls and the Trolltrace workers simultaneously get rick-rolled. Gerald escapes the conference room by entering the code (9). He then, by instruction of the trolls and the Trolltrace workers, tries to shut down Trolltrace, but Lennart stops him. They then have a debate about why they really troll and Gerald ends up kicking Lennart in the crotch and throwing him over a railing to his death. He then helps to deactivate Trolltrace. He returns home to a delighted Sheila and an angry Kyle and Ike.
Denmark uses Heidi's emoji analysis to track down trolls in Fort Collins. They release the internet history of everyone in Fort Collins, leading one of the victims of Anthony Webster's trolling to kill Andrew. The Danish then reveal they plan to release the internet history of anyone in Colorado. Kyle and Ike go to the church to persuade everyone to get the president to bomb Denmark, not knowing Gerald is in Denmark. The town use Mr. Slave to get Garrison to bomb Denmark. Kyle discovers his dad is in Denmark and persuades Garrison not to bomb Denmark. Kyle them locks Sheila in the pantry to use the computer and sort things out. He gets all the boys (besides Butters and Cartman) to help him troll as Skankhunt42. Sheila escapes from the pantry, so Kyle and Ike escape. Kyle gets a call from Herbert Garrison praising him for what he is doing. Kyle then calls Butters to ask where he is and why he isn't helping, and Butters reveals SpaceX has enough energy to beat TrollTrace. Meanwhile, Sheila goes to Laura Tucker's house to talk to Laura about Ike. Laura tells Sheila about TrollTrace, which has now gone active. Sheila looks up Ike's history and discovers he isn't the troll. Laura tells her that the person she should look up the internet of is her husband. Sheila then proceeds to look up Gerald's internet history but Kyle manages to shut down the internet.
The girls start to blame Skankhunt42's behavior on all boys and break up with their boyfriends. Charlotte breaks up with Butters, which leads to a change in him. Butters starts leading a movement to be proud of being a boy by pulling his wiener out. He looks down on Cartman for siding with a girl. PC Principal tries to stop the gender wars by getting Bill Clinton in, who tells the children about Bill Clinton's Gentleman's Club. He gets Stan to talk to Wendy about his feelings, which doesn't work out due to Butters coming and pulling his wiener out. Bill goes to Butters' house to talk to him about women being angry and how they must do something big to save their gender. Butters gets frightened and runs off to try and get to Mars along with Heidi and Eric. He tells Cartman what Bill told him, which Cartman then proceeds to tell the SpaceX workers.
Cartman, without technology, becomes lonely until he meets with Heidi, who quit social media after continually being trolled by Skankhunt42. Heidi shows Cartman her vagina at the end of "The Damned". They then start dating. When Kyle comes for Cartman's help to stop Butters, Cartman denies it as he is "out of it now". Heidi gets an idea to do a fundraiser for the people of Denmark, known as Danishes for Denmark. This doesn't work and Cartman comforts her. The two send a video to Denmark stating that they will help them. When the Danish reveal they plan to reveal everyone's internet history, Cartman worries Heidi will find out about his bigoted past. Butters tells Cartman from experience that girls will "leave poop on his heart". Cartman tries to get Heidi to say something funny, but she is too busy working out how to get to Mars. After SpacweX is destroyed, Heidi says to Cartman that their dreams should be put on hold. By the end of the season, Heidi and Cartman are still a couple.
Cartman persuades Heidi to come with him to Mars so they can escape the reactions of people once everyone's internet history is revealed. They head to Space X, where they find out they aren't the only ones who want to go to Mars. Butters arrives and Cartman believes Butters has a plan to steal Heidi from him. They meet Elon Musk, who shows them round and reveals they aren't ready for Mars. Butters steps in and says that Heidi can help them get to Mars. Heidi converts the calculations to emojis and finds there is a part that is out of sequence, essentially solving the problem. Cartman discovers what will happen when they get to Mars and tries to stop it. He evacuates the building and, with the help of Kyle, he manages to destroy SpaceX. He then suggests to Elon that he should "go back to your little cars", referring to Tesla Motors
2016 presidential election
Continuing on from the previous season, Herbert Garrison is still running for president, along with Caitlyn Jenner. The two celebrate being ahead in the polls until Garrison realizes he doesn't know what he will do when he's in power. He then tries to get people to vote for Hillary Clinton, but things don't go to plan. When he tells the world he doesn't know what he is doing, Hillary replies with "My opponent is a liar, and he cannot be trusted" by order of her aides. Unfortunately, this increases Garrison's votes. In "Douche and a Danish", Garrison is told that he may lose votes if he insults women, so he insults them and his votes go down. When his aides and a bunch of angry Republicans chase after him, he runs back to South Park and tries to resume his job as teacher like nothing happened. Unfortunately, his aides manage to pull him out of the school. He runs until he gets to the Community Center and then goes in. There, he is greeted by Randy who explains to him that memberberries and J.J. Abrams are causing people to vote for Garrison. Randy persuades Garrison to give a speech "from the heart" to convince people to vote for Hillary. Meanwhile, Hillary's aides come to speak to her and tell her about Denmark's plan to release everyone's internet history. They also tell her that the only one that can save her is Skankhunt42. Mr. Garrison wins the election and accepts his presidential victory after being infected by the memberberries. He then travels to South Park (Location) and forces PC Principal and other people who doubted him to perform fellatio. He is called to the pentagon, where he finds out about Trolltrace. The foreign secretary in Britain calls to tell him not to eat the "memburries" (memberberries). Garrison, having been affected by the memberberries, yells at him. He is persuaded to bomb Denmark by Mr. Slave and then not to by Kyle. He discovers Kyle plans to troll until Trolltrace goes down and praises him for it. At the end of the episode, President Garrison sits it the Oval Office in front of an army of memberberries.
When the girls sit out the national anthem, the government gets J.J. Abrams to reboot the anthem. Abrams version lets people stand or sit, ruining Mr. Garrison's plan to sit out the national anthem. Randy is introduced to memberberries, which help him relax until they start sparking racist comments. He then creates a memberberry addiction club and discovers memberberries are causing people to vote for Mr. Garrison. Randy and Garrison try to destroy the berries, but all their attempts failed. The berries escape and manage to put a berry in a drink, which the waiter serves to Caitlyn Jenner. Caitlyn infects Randy with the memberberries, who then infects Sharon and Shelly. The memberberries travel to the White House, where their leader tells them he plans to bring back the real Stormtroopers.
To promote the season, Comedy Central had mobile billboards placed in key locations in seven cities around the United States. Each billboard featured an image from the series that bore a connection to the location in which it was placed.
- In Los Angeles, a billboard was placed in front of the headquarters of the Church of Scientology, which was parodied in the controversial 2005 episode "Trapped in the Closet".
- In Washington, D.C., a billboard was placed in front of the Lincoln Memorial and the White House. It featured Barack and Michelle Obama, whose relationship was parodied in the 2008 episode "About Last Night...".
- In Lakewood, Colorado, a billboard was placed in front of the city's Casa Bonita restaurant, which was a central plot point of the 2003 episode "Casa Bonita".
- In Salt Lake City, Utah, a billboard was placed in front of the headquarters of the Mormon Church, which was parodied in the 2003 episode "All About Mormons".
- In Menlo Park, California, a billboard was placed in front of the headquarters of Facebook, which was parodied in the 2010 episode "You Have 0 Friends".
- In New York City, a billboard was placed in front of the campaign headquarters of Donald Trump and Hillary Clinton, whose presidential campaigns were parodied in this season's premiere "Member Berries" as well as "Where My Country Gone?".
- In Buffalo, New York, a billboard was placed in front at the United States' border with Canada, whose culture and relationship with the United States has been parodied in the feature film South Park: Bigger, Longer & Uncut, and various episodes such as "Royal Pudding".
All of the billboards included the caption "We've Been There." In some of the locations, personnel of the organizations were displeased to have the billboards outside their locations and asked the billboard operators to leave, including the Los Angeles and both Washington, D.C landmarks. Comedy Central's Chief Marketing Officer Walter Levitt stated, "That was all expected, and we completely understand why. We knew it was risky. We did this stunt because we thought it was a great way to remind South Park fans of all the amazing moments of the past 19 seasons and truly a perfect way to celebrate the 20th season.