Thursday -- Themed this time

I'm starting off with a couple pictures of Stone Mountain even though it has nothing to do with Peter A. Collins's delightful puzzle, so that my Yankee friends who were unfamiliar with this monument on Monday will have some idea what it's about. Don't thank me, I'm going to be asking you to return the favor in just a moment, but first our ever-popular:
SPOILER WARNING: Don't read any further until you've done today's New York Sun Crossword Puzzle. New York Sun puzzles are every bit as good as the more well-known New York Times, and they're indisputably better in one way -- they're free. You can download this puzzle and join in on the fun here.

Station Breaks by Peter A. Collins. The stations in question break
into the themed entries thusly 18A: Upper Strata (TOP LAYERS) with
PLAY station breaking in,
62A: Participate in "American Idol" (SING A SONG) (Gas station). 24A: Aaron Spelling series of 1989 (MALIBU SHORES) (BUS) (Mr. Spelling has developed a lot of long-running
hit series – "Beverly Hills 90210", "The Love Boat", "Charlie's
Angels" -- "Malibu Shores" was one of his few misfires – it only lasted
ten episodes.) 39A George Plimpton book on hockey (OPEN NET) (hiding
Penn Station) George Plimpton was famous for many things, the Paris
Review, wrestling Robert Kennedy's assassin Sirhan Sirhan to the ground, for pulling one of the best April Fools jokes ever and for books where he wrote about what it was like to participate in professional sports. In addition to "The Open Net" he did "The Bogey Man" (Golf) "Paper Lion" (Football) and "Out of My League" (baseball) and more.
51A: The tenth and beyond (EXTRAINNINGS) which hides TRAIN station and that bring me to what I wanted to ask my Northern neighbors. I recently went on my first train ride since I was a kid. I rode to Stamford, Connecticut, and I couldn't help but notice that the train station in Baltimore,
Newark, Philadelphia and New York City (and maybe one or two more I've
forgotten) were all named Penn Station. Why is that?
Is Penn Northern for train? Or did y'all just run out of names? And if "Penn" and "Train" are
synonymous, is it redundant to include both in this puzzle?

Other entries of note:

15A: Bath half-bath half (LOO) Only four words but a very confusing clue A loo is a toilet and the smallest half-bath in the world has a complete commode. But after much deliberation we have decided to allow this clue.

1D: Sin city? (SODOM) I guess Sodom and Gomorrah were twin sin
cities. The Bible is kind of vague of what kind of gross immorality
these two burgs were full of, although it's not too hard to figure out
what went on in Sodom, since it gave its name to a practice that
probably wouldn't pass the breakfast table test. But what the heck did did they do
in Gomorrah?

19D: Yarnell of Shields and Yarnell (LORENE) Mimes seem to inspire
strong emotions in people – mostly negative. Hard to believe that
once mimes had their own television show, in prime time no less.

30D: Sound from a bowl (ROAR) That's Rose Bowl or Super Bowl not Tupperware.

44D: Steed, e.g. (AVENGER) Steed, John Steed. My favorite secret agent.

55D: It'll put stripes on your dog (GRILL) One of those clues that can drive you crazy if you can't shake the canine-zebra visual.

31D: Caan job? (ACTOR) It seems like James Caan's job is ACTING and ACTOR is his job title, but I won't quibble.

43A: Place associated with the Sundance Kid (ETTA) Crossword constructors have at least three ETTAs to choose from -- James, Jones and Place. By far the most mysterious member of this triumphirate is Ms. Place. To paraphrase Bob Dylan, the only thing we know for sure about Etta Place is that her name wasn't Etta Place. She was probably from Texas but might have come from back East, she might have been a teacher, a prostitute or neither, may have married Harry Alonzo Longabaugh or not, and she died either in 1922, 1924 or 1966 (!)

70A: It lasts 34 wks. (DST) This was actually the toughest one from me and the one I saved for last. Lasting 34 weeks didn't turn on any light bulbs and I didn't know 52D: Abstract artist Martin. Had to do the alphabet game to get my Aha!