This has been a week for tradition. We’ve just wrapped up the World Series and anticipate a presidential election, a leap-year tradition. Television remains constant as well. “60 Minutes” continues to rank among the top-20 shows, as it has since 1968. “Law & Order” returns this Wednesday on NBC, where it has been broadcast since 1990. And “The Simpsons” (7 p.m., Sunday, Fox) offers “Treehouse of Horror XIX.” Surviving 19 seasons is remarkable, but remaining funny, provocative and audacious is something else. Tonight’s trilogy of shocking tales sends up fears of voting-machine rigging and transformer robots run amok. It offers a gruesome look at advertising, complete with a “Simpsons” take on the “Mad Men” title sequence. You’ll never look at a TV commercial “starring” a dead celebrity the same way again.

“Treehouse” concludes with a gruesome and at the same time affectionate nod to that animated classic “It’s the Great Pumpkin, Charlie Brown.” Not to be missed.

¢ Peter Gallagher and ballet dancer Ethan Stiefel reprise their roles in “Center Stage: Turn it Up” (7 p.m., today, Oxygen), a sequel to “Center Stage,” a drama set in the competitive world of ballet.

¢ Once known as The Learning Channel, the TLC network has carved out a special niche with viewers fascinated by the unusual. Shows dedicated to families of little people or parents dealing with multiple births have become a staple, and so have documentaries about people beset by staggering weight or freakish medical mysteries. Sunday’s lineup includes “Paralyzed and Pregnant” (6 p.m.) and “I Didn’t Know I Was Pregnant” (7 p.m.).

The documentary “Purity Balls” (8 p.m., Sunday, TLC) chronicles social rites in which a father takes a public pledge to defend his daughter’s virginity. Much like the child beauty pageants made famous and/or infamous by the Jon Benet Ramsey case, these purity functions appear wholesome to some and creepy to others.

At this rate, the network may need a logo makeover. There’s only a one-letter difference between TLC and TOC, The Oddity Channel. It could become TUC, The Uncomfortable Channel. Or, for that matter, TIC, The Icky Channel.

Saturday’s highlights

¢ The clock ticks as Cutter fights captivity on the second-season finale of “Primeval” (8 p.m., BBC America).

¢ Ben Affleck hosts “Saturday Night Live” (10:30 p.m., NBC), featuring musical guest David Cook.

Sunday’s highlights

¢ Scheduled on “60 Minutes” (6 p.m., CBS): a fake federal agent who “arrested” 20 Missouri citizens; new hope for amputees; returning veterans barred from their old jobs.

¢ Competitors trek from Cambodia to India on “Amazing Race” (7 p.m., CBS).

¢ “Five Years on Mars” (7 p.m., National Geographic) profiles the two roving robots, Spirit and Opportunity, that have been mapping and exploring the Martian surface since 2003.

¢ The thriller “The Last Enemy” concludes on “Masterpiece” (8 p.m., PBS, check local listings).

¢ Set on the crossroads of local politics and organized crime, “The Brotherhood” (7 p.m., Showtime) enters its third season.