The 42nd season of “Saturday Night Live” came in with a bang and is now assured of going out with one, too: NBC will air the final four episodes of the season live coast to coast, a first in “SNL” history starting April 15. That means that the 11:30 telecast in New York will be seen at 8:30 p.m. on the West Coast.

In addition, Melissa McCarthy will host the May 13 edition. McCarthy — or at least her Sean Spicer — is one of the reasons “SNL” has particularly insinuated itself into the “zeitgeist” (NBC’s word) this year, and an obvious reason why the network decided to go live coast to coast.

In a statement, NBC chief Bob Greenblatt said, “ ‘SNL’ — enjoying its most popular season in two decades — is part of the national conversation, and we thought it would be a great idea to broadcast to the west and mountain time zones live at the same time it’s being seen in the east and central time zones. That way, everyone is in on the joke at the same time. Kudos to Lorne Michaels, the producers and cast for making ‘SNL’ one of the most relevant and anticipated shows in the zeitgeist.”

Along with McCarthy, the other hosts will be Jimmy Fallon (April 15), Chris Pine (May 6) and Dwayne Johnson (May 20), who will close out the season.

“SNL” — like much of the rest of the late-night shows, which have also enjoyed a so-called “Trump bump” this year — has had a significantly bigger bump, mostly because seven-day playback on other platforms like Hulu has been torrid.

But the obvious question is, why hasn’t “SNL” or NBC done this before? And will this be on the vanguard of a new fully live coast-to-coast “SNL” in the future? One reason is content. Simply put, what can get by censors at 11:30 p.m. (or after midnight) might have faced a somewhat higher hurdle at 8:30 p.m.

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This move will test just how high that hurdle is.

Nevertheless, Saturday nights have been ratings dead zones on NBC, and, for the most part, on the other networks too. A fully “live” “SNL” coast to coast should remedy that, at least for May sweeps.