Theme: Stay Tuned - We'll Be Right Back - The word, "STATION", is 'broken' into two sections and they are part of the theme entries.
20A. Pittsburgh fan base, collectively : STEELER NATION
27A. Philatelist's pride : STAMP COLLECTION
49A. Annual political speech : STATE OF THE UNION
57A. Commercial interruptions literally found in this puzzle's three other longest answers : STATION BREAKS
Argyle here. Notice the nice progression in the break-up of the word, station, 2-3-4. And even though the sides are broken into three-letter words, there wasn't an overabundance of them. I'm happy; are you?
Across:
1. Leftover bit : SCRAP. Hah! I was already typing ORT before I saw how many letters there were.
6. Kitchen meas. : TBSP. (tablespoon)
10. Highland tongue : ERSE
14. Thrill to pieces : ELATE
15. Commuter's option : RAIL
16. Cuts short : LOPS
17. "Understood!" : "GOT IT!"
18. Egg on : URGE
19. Debt-heavy corp. takeovers : LBO's. (leveraged buyout)
23. A pop : PER. Each.
24. Confirmation or bar mitzvah : RITE
25. Tons of, casually : LOTSA. (a lot of)
31. Pet welfare org. : ASPCA. (American Society for the Prevention of Cruelty to Animals)
32. Tie up loose ends? : SEW
33. Shed a few tears : CRY. Extensive write-up goes with this if you go to YouTube.
34. "Bus Stop" playwright : INGE. William
37. Radar's favorite drink : NEHI. (grape)
40. Butter on the farm? : RAM. 30D. 40-Across mate : EWE
43. Windy City trains : ELs. Elevated trains in Chicago.
45. Solemn promises : OATHS
54. Appeared on TV : AIRED
55. Penlight batteries : AAA's
56. AFL affiliate : CIO. (American Federation of Labor and Congress of Industrial Organizations)
61. Just as you see it : AS IS
62. City near Sacramento : LODI. CCR's take on Lodi(3:08).
63. Young neigh sayers : COLTS. Cute one.
65. Adjust, as strings : TUNE
66. Close : SHUT
67. Slippery as __ : AN EEL
68. Israel's only female prime minister : MEIR. (Golda)
69. Nile threats : ASPS. The crosswords are full of them, too.
70. Toy bear named for a president : TEDDY
Down:
1. Line piece: Abbr. : SEG. (segment)
2. Places to hide skeletons? : CLOSETS
3. Dilapidated dwelling : RAT TRAP
4. End in __: come out even : A TIE
5. He refused to grow up : PETER PAN
6. Faithfully following : TRUE TO
7. Oil units : BARRELS
8. Talk with one's hands : SIGN
9. Earnest request : PLEA
10. Nixon attorney general Richardson : ELLIOT. He resigned rather than obey President Nixon's order to fire special prosecutor Archibald Cox.
11. Like some of Michael Jackson's moves : ROBOTIC. @1:15
12. Advertiser : SPONSOR
13. Twisty curve : ESS
21. DMV certificate : LIC. (license)
22. Dr. Mom's specialty : TLC. (Tender Loving Care)
23. "This is your brain on drugs," e.g. : PSA. (public service announcement)
26. Unspecified quantity : ANY
28. 12th century opener : MCI. 1101
29. Deighton who wrote the "Hook, Line and Sinker" trilogy : LEN. Spy Hook, Spy Line, and Spy Sinker. It is the middle trilogy of a set of three trilogies. Man, that's a lot of reading.
35. Prefix with thermal : GEO. As a prefix: geo- is taken from Greek, meaning "earth", usually in the sense of "ground or land".
36. Santa's helper : ELF
38. Pet on your lap, maybe : HOUSE CAT. And anywhere else they damn please to lie. Check out today's Garfield.
39. Author Fleming : IAN. related, 42D. Bond's is shaken, not stirred : MARTINI
40. Cape Town's country: Abbr. : RSA. (Republic of South Africa)
41. Being debated : AT ISSUE
44. Comedy genre : STAND-UP
46. Got a giggle out of : TICKLED
47. Raised, as a flag : HOISTED
48. Nestlé's __-Caps : SNO
50. Movie trailer, e.g. : TEASER
51. Boston summer hrs. : EDT. (Eastern Daylight Time)
52. Nuns' clothing : HABITS
53. Kernel holder : EAR
58. Rick's love in "Casablanca" : ILSA
59. Fireworks responses : OOHs. Followed by aahs.
60. Top-shelf : A-ONE
61. Way to check your balance, briefly : ATM. Check to see if it was made by NCR.
64. Sneaky : SLY
Argyle