Broadcast television may have a lock on hit original comedies, but that’s no longer the case in drama, where the ratings gap has closed considerably of late.

Basic cable’s hottest scripted hours of the fall — AMC’s “The Walking Dead” plus FX’s “Sons of Anarchy” and “American Horror Story” — were competitive among adults 18-49 against Big Four offerings during the November sweep and actually moved to the lead in the more narrow 18-34 category, according to Nielsen.

On Nov. 13, “The Walking Dead” averaged a 3.2 rating among adults 18-49, beating out original episodes of ABC’s competing “Desperate Housewives” (3.0) and CBS’ “The Good Wife” (2.0) in the same Sunday at 9 timeslot.

But it wasn’t even close among the 18-34 crowd, where the zombie skein did a 3.4, ahead of “DH” (2.5) and more than three times “Good Wife” (1.0).

Similarly, the Tuesday drama battle on Nov. 15 saw FX’s “Sons of Anarchy” hit a big 2.2 rating in 18-49 — close behind “Unforgettable” on CBS (2.4) and ahead of ABC’s “Body of Proof” and NBC’s “Parenthood” (both at 2.0).

But again, adults under 35 were drawn more to the motorcycle club stories on “Sons” (2.2 rating) than the family drama “Parenthood” (1.5) or the crime hours “Unforgettable” (1.2) and “Body of Proof” (1.1).

And one night later, haunted house skein “American Horror Story” grew to a 1.8 rating in adults 18-49; while this was fourth among dramas for its hour, it was a good showing in a crowded hour that includes CBS vet “CSI” (2.6), hot ABC rookie “Revenge” (also 2.6) and NBC’s top drama, “Law & Order: SVU” (1.9).

And for the first time, “Horror Story” led all of its broadcast drama competition in adults 18-34, with its 2.2 edging out the 2.0 for “Revenge” and well ahead of the 1.4 for “CSI” and “SVU.”

Adults 50 and over are still largely enamored of the more traditional broadcast offerings, and that’s why these shows tower over their cable counterparts in total viewers. On Tuesdays this fall, for example, “Sons of Anarchy” has been competitive demo-wise despite drawing less than half the overall audience (about 4 million) of either “Unforgettable” (12 million) or “Body of Proof” (10 million).

But the business is built around reaching harder-to-reach younger adults, and the trend line isn’t looking good for old-school broadcast dramas.