Not sure about the USMC but the RAF changed their rank structure per squadron since WW2, though I'm not sure of the change over date.
WW2:
Wg Cdr usually in charge of a bomber squadron
Sqn Ldr usually in charge of a fighter squadron (with Wg Cdr/Gp Capt per Wing)
Now it is just:
Wg Cdr in charge of a squadron (Lt Col equiv)
Fighter squadrons went up in size to around 16 but have now gone down to 12-13.