Broadway perked up last week, with the Labor Day weekend helping to ring in a bit more biz than the prior frame.

The coming week, of course, usually brings the dreaded September slump, marked in previous years by a precipitous drop in weekly sales.

This year the falloff looks likely to be less severe — if only because the B.O. seems to have begun its seasonal decline earlier than usual.

One theory explains the premature slippage, which saw overall sales drop $2 million for the week ended Aug. 29, as the result of the early start of the school year around the country, sending tourists back home earlier than usual.

It follows, then, that the big slide that usually comes this week might be a bit less dramatic than normal.

In that respect, fall may end up looking like the summer season, when B.O. softened throughout August, rather than suffering one gargantuan drop as it did in 2008, when sales plummeted by more than $4 million in the frame following Labor Day.

For the moment, at any rate, the Main Stem held steady, with total sales up about $500,000 to $16.7 million for 22 shows on the boards.

Many individual productions posted gains, although few were huge — at least besides the leap made by “The Addams Family” ($1,079,425), vaulting upward by more than $300,000thanks to Nathan Lane’s return from vacation. “Promises, Promises” ($1,006,844) also returned to the millionaires’ club following a couple of weeks’ absence.

Last-minute sales helped “Come Fly Away” ($703,952) step up by about 11% in its final frame on the boards, while the slow-burning “Memphis” ($900,642) got a bit hotter.

The dips posted over the frame were almost entirely unremarkable. “Mary Poppins” ($844,188) has come down from its summer stint in the millionaires’ club, although the show nonetheless remained in the top three for attendance.

One new production joined Broadway’s fall lineup, with the Roundabout Theater Company’s revival of “Mrs. Warren’s Profession” ($134,547) playing its first five previews. Activity will kick into high gear later this month as more and more shows begin previews for the glut of October opening nights.